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Trace element variation in olivine in the Skaergaard intrusion: petrologic implications
박병준,장윤득,이인성,김정진,추창오 한국지질과학협의회 2010 Geosciences Journal Vol.14 No.4
Olivine from the Layered Series (LS), Upper Border Series (UBS), and Marginal Border Series (MBS) of the Skaergaard intrusion was analyzed to examine trace element variations. In general, olivine from all three series shows similar trends in trace elements with differentiation. Ba, Cs, Rb, and Sr, acted as excluded trace elements and the transition elements, Co, Cr, Cu, Ni, Sc, Zn, and V, are included in Skaergaard olivine. Owing to the high DNi in olivine, Ni decreases with differentiation in both olivine and the calculated Skaergaard magma. The low concentration of Cr in olivine is attributable to early depletion of Cr by pyroxene crystallization. Decreases in the abundances of V and Co are related to the onset of magnetite crystallization and the separation of immiscible Co-rich sulphide. In general, calculated partition coefficients (Di) for Skaergaard olivine show similar trends in the LS, UBS, and MBS. Calculated Di’s for Sc, Cr, and Ga in olivine, progressively increase, and Di’s for Zr, Nb, Hf, Cs, Ta, Th, and U progressively decrease, with differentiation. The systematic variation in trace element contents of Skaergaard olivine during differentiation would appear to preclude the possibility of any significant injection of new magma into the chamber during differentiation. The Ni content in Skaergaard olivine systematically decreases with differentiation as would be expected if the intrusion remained a closed system. In fact, no abrupt increases are observed in the abundances of any of the transition metal in olivine during differentiation.
박병준,김홍관,최용수,김진국,조재일,최준영,심영목 대한영상의학회 2015 Korean Journal of Radiology Vol.16 No.4
The maximum standardized uptake value (SUVmax) of pulmonary mucoepidermoid carcinoma (PMEC) in fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) was evaluated as a preoperative predictor of pathologic grade and survival rate. Twenty-three patients who underwent preoperative PET/CT and complete resection for PMEC were enrolled. The optimal cut-off SUVmax for tumor grade was calculated as 6.5 by receiver operating characteristic curve. The patients were divided into a high SUV group (n = 7) and a low SUV group (n = 16). Clinicopathologic features were compared between the groups by χ2 test and overall survival was determined by Kaplan-Meier analysis. The mean SUVmax was 15.4 ± 11.5 in the high SUV group and 3.9 ± 1.3 in the low SUV group. All patients except one from the low SUV group had low grade tumors and all had no nodal metastasis. The sensitivity and specificity of SUVmax from PET/CT for predicting tumor grade was 85.7% and 93.8%, respectively. During the follow-up period (mean, 48.6 ± 38.7 months), four patients from the high SUV group experienced cancer recurrence, and one died of cancer. In contrast, none of the low SUV group had recurrence or mortality. Five-year overall survival rate was significantly higher in the low SUV group (100% vs. 71.4%, p = 0.031). Pulmonary mucoepidermoid carcinoma patients with high SUVmax in PET/CT had higher tumor grade, more frequent lymph node metastasis and worse long-term outcome. Therefore, PMEC patients with high uptake on PET/CT imaging might require aggressive mediastinal lymph node dissection and adjuvant therapies.
Dynamics of a Polyelectrolyte under a Constant Electric Field
박병준 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.9
We perform a molecular dynamics simulation of a polyelectrolyte in a viscous fluid under an external electric field to study the dynamics of gel-free electrophoresis. To incorporate the hydrodynamic effects, we employ a coarse-grained description of water by using multiparticle collision dynamics. We use a screened Coulomb interaction among the monomers and explicit monovalent counterions to model the electrostatic interactions in an ionic solution. The mobility of the polyelectrolyte μ is obtained as a function of the molecular weight N, the electric field strength E, and the Debye screening length of the solvent . The mobility is found to be independent of N for large N and to exhibit a maximum at a certain N for a large , which are in agreement with experimental results. The dependence of μ on E is also examined and discussed by considering the effects of an electric field on counterion condensation. The dependence of μ on shows a discrepancy between our simulation and experiments, which implies that the added salts not only screen out the Coulomb interaction but also participate in the counterion condensation significantly.
Multiparticle Collision Dynamics Simulation of a Polymer in a Viscous Fluid
박병준 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.4
We perform a hybrid molecular dynamics simulation of a polymer immersed in a viscous liquid. Using the multiparticle collision dynamics algorithm to incorporate the hydrodynamic effects, we examine static and dynamic properties of a self-avoiding flexible polymer. The diffusion coefficient of the polymer is found to be proportional to <i>N<sup>−υ</sup></i>, where <i>N</i> is the molecular weight of the polymer and υ = 3/5 is the swelling exponent, as predicted by the Zimm model. The velocity autocorrelation function of the center of mass of the polymer is obtained as a function of time <i>t</i>, which shows an algebraic decay as <i>t</i><sup>−3/2</sup> at long-time scales. Our results confirm the theoretical prediction for the dynamical properties of a polymer and show the validity of the hybrid simulation scheme in studying the dynamics of a polymer in a viscous fluid.
35 kWh급 플라이휠용 초전도 베어링의 댐핑 특성평가
박병준,정세용,한상철,한상진,이대화,한영희,Park, B.J.,Jung, S.Y.,Han, S.C.,Han, S.J.,Lee, D.H.,Han, Y.H. 한국초전도학회 2012 Progress in superconductivity Vol.14 No.1
Superconductor flywheel energy storage system (SFESs) is an electro-mechanical battery with high energy storage density, long life, and good environmental affinity. SFESs have been developed for application to a regenerative power of train, the storage of distributed power sources such as solar and wind power, and a power quality improvement. As superconductor bearing is completely passive, it is not necessary to control a system elaborately but accurate analysis in mechanical properties of the HTS bearing is very important for application to SFESs. Stiffness and damping properties are the main index for evaluation the capacity of HTS bearings and make it possible to adjust rotordynamic properties while operating the rotor-bearing system. The superconductor bearing consists of a stator containing single grain YBCO bulks, a ring-type permanent magnet rotor with a strong magnetic field that can reach the bulk surface, and a bearing support for assembly to SFESs frame. In this study, we investigated the stiffness and damping properties of superconductor bearings in 35 kWh SFESs. Finally, we found that 35 kWh superconductor bearing has uniform stiffness properties depend on the various orientations of rotor vibration. We discovered total damping coefficient of superconductor bearing is affected by not only magnetic damping in superconductor bulk but also external damping in bearing support. From the results, it is confirmed that the conducted evaluation can considerably improve energy storage efficiency of the SFESs, and these results can be used for the optimal capacity of superconductor bearings of the SFESs.