• Journal of Integrative Natural Science
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• v.5 no.2
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• pp.79-83
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• 2012

Trialkyltin n-$Bu_3SnH$, an endocrine disruptor, was slowly converted by the catalytic action of group 4 $Cp_2MCl_2$/Red-Al (M = Ti, Zr, Hf) to produce two phases of products: one is an insoluble cross-linked solid, polystannane in 7-23% yield as minor product via redistribution/dehydrocoupling combination process, and the other is an oil, hexabutyldistannane in 69-90% yield as major product via simple dehydrocoupling process. Redistribution/dehydrocoupling process first produced a low-molecular-weight oligostannane possessing partial backbone Sn-H bonds which then underwent an extensive cross-linking reaction of backbone Sn-H bonds, leading to an insoluble polystannane. This is the first exciting example of redistribution/dehydrocoupling of a tertiary hydrostannane catalyzed by early transition metallocenes.

• Journal of the Korean Ceramic Society
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• v.39 no.9
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• pp.818-821
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• 2002

The grain boundary resistivity of a 1-mol%-$Al_2O_3$-dopedd CaO-Stabilized Zirconia(CSZ) specimen was determined by impedance spectroscopy using sub-millimeter-scale electrodes. At the initial stage of sintering, the grain-boundary resistivity of the specimen interior was observed to be higher than that of the surface. However, upon further sintering the boundary resistivity of the specimen interior became lower than that of the surface. The results were explained in terms of a redistribution of the intergranular liquid phase. The liquid phase was predicted to initially coagulate at the interior of the specimen then spread outward during sintering.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.2
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• pp.26-33
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• 1997

In this study effect of residual stress and its redistribution in weldment on the fatigue crack propagation was investigated. Fatigue tests were conducted by the center notched specimens machined with welded plate. The residual stress and its redistribution after the crack growth were measured by the magnetizing stress indicator and hole-drilling method. Fatigue crack propagation was estimated by the specimens having residual stress redistributed after the cracks growth and having the effects of crack closure. Crack growth rates were predicted and compared with experimental results. It had been found that the predicted crack propagation rates have a good agreement with experimental results when the redistribution of residual stress was considered.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.165-169
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• 1996

In this study residual stress in weldment was considered about the effect on the fatigue propagation and about the effect of redistribution of residual stress. Then, fatigue tests were conducted by the center notched specimens machined with welded plate. The residual stress and its redistribution after the crack growth were measured by the magnetizing stress indicator and hole-drilling method. Fatigue crack propagation was estimated by the specimens having residual stress redistributed after the cracks growth and having the effects of crack closure. Crack growth rates were predicted and compared with experimental results. It had been found that the predicted crack propagation rates have a good agreement with experimental results when the redistribution of residual stress was considerd.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.7
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• pp.2234-2245
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• 1996

In this study residual stress in weldment was considered about the effect on the fatigue propagation and about the effect of redistribution of residual stress. Then, fatigue tests were conducted by the center notched specimens machined with welded plate. The residual stress and its redistribution after the crack growth were measured by the magnetizing stress indicator and hole-drilling method. Fatigue crack propagation was estimated by the specimens having residual stress redistributed after the cracks growth and having the effects of crack closure. Crack growth rates were predicted and compared with experimental results. It had been found that the predicted crack propagation rates have a good agreement with experimental results when the redistribution of residual stress was considerd.

• The Korean Journal of Nuclear Medicine
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• v.38 no.3
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• pp.218-224
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• 2004

We compared rest perfusion PET with redistribution perfusion SPECT to investigate the concordant rate between PET and SPECT images and analyze the discordant pattern. Materials and Methods: Rest N-13 ammonia and F-18 FDG PET were performed on 18 patients with old myocardial infarction and left ventricular dysfunction whose dipyridamole - 4hr redistribution TI-201 SPECT showed one or more severe fixed defects. Regional perfusion and metabolism were evaluated visually and quantitatively with 5-segment myocardial model. Results: There were high concordant rate in uptake pattern (80/90 segments, 88.9%) and high correlation coefficient on quantitative analysis (R=0.81, p<0.001) between redistribution TI-201 SPECT and N-13 ammonia PET images. Nine of 18 patients had SPECT-PET concordant pattern (Group I). Ten segments (9 in inferior wall, 1 in apex) from the remaining 9 patients showed SPECT-PET discordant pattern with abnormal TI-201 defect and near normal N-13 ammonia uptake (Group II). The diastolic and systolic left ventricular dimensions were significantly increased in Group II compared to those of Group I. When attenuation uncorrected N-13 ammonia PET images were reconstructed in Group II, it resulted in PET images with severe inferior wall defects nearly identical to those seen in redistribution TI-201 SPECT images. Conclusion: Redistribution TI-201 SPECT images showed high concordant rate and correlation with rest N-13 ammonia PET images. Most of discordant segments had fixed thallium defects in inferior wall with nearly normal N-13 ammonia uptake, which may result from severe left ventricular dilatation and attenuation by the left hemidiaphragm and cardiac blood pool.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.171-171
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• 1999

We studied the charge redistribution in the Pt-M (M=Cu, Co) alloys by X-ray Absorption Near Edge Spectroscopy(XANES) and X-ray Photoelectron Spectroscopy(XPS). These analysis tools provide us information about the charge transfer in the valence band of intermetallic bonding. The samples were prepared by arc-melting method. After annealing this samples in vacuum for several hours, we cold get the ordered samples, which were confirmed with XRD analysis. the core and valence level energy shift in these system were investigated by Mg $K\alpha$(1253.6eV) x-ray source for Pt-Co alloys and monochromatized Al $K\alpha$ (1486.6eV) for Pt-Cu alloys. Pt L2, L3-edge, and Cu, Co K-edge XANES spectra were measured with the total electron-yield mode detector at the 3Cl beam line of the PLS (Pohang light source0. from the changes of White line (WL) area and the core level shifts of the each metal sites, we can obtain the information about the electrons participating in the intermetallic bonding of the Pt-Cu and Pt-Co alloys.

• Korean Journal of Radiology
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• v.23 no.10
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• pp.986-997
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• 2022

Objective: Whether metabolic redistribution occurs in patients with white matter hyperintensities (WMHs) on magnetic resonance imaging (MRI) is unknown. This study aimed 1) to propose a measure of the brain metabolic network for an individual patient and preliminarily apply it to identify impaired metabolic networks in patients with WMHs, and 2) to explore the clinical and imaging features of metabolic redistribution in patients with WMHs. Materials and Methods: This study included 50 patients with WMHs and 70 healthy controls (HCs) who underwent ¹⁸F-fluorodeoxyglucose-positron emission tomography/MRI. Various global property parameters according to graph theory and an individual parameter of brain metabolic network called "individual contribution index" were obtained. Parameter values were compared between the WMH and HC groups. The performance of the parameters in discriminating between the two groups was assessed using the area under the receiver operating characteristic curve (AUC). The correlation between the individual contribution index and Fazekas score was assessed, and the interaction between age and individual contribution index was determined. A generalized linear model was fitted with the individual contribution index as the dependent variable and the mean standardized uptake value (SUV_mean) of nodes in the whole-brain network or seven classic functional networks as independent variables to determine their association. Results: The means ± standard deviations of the individual contribution index were (0.697 ± 10.9) × 10^-3 and (0.0967 ± 0.0545) × 10^-3 in the WMH and HC groups, respectively (p < 0.001). The AUC of the individual contribution index was 0.864 (95% confidence interval, 0.785-0.943). A positive correlation was identified between the individual contribution index and the Fazekas scores in patients with WMHs (r = 0.57, p < 0.001). Age and individual contribution index demonstrated a significant interaction effect on the Fazekas score. A significant direct association was observed between the individual contribution index and the SUV_mean of the limbic network (p < 0.001). Conclusion: The individual contribution index may demonstrate the redistribution of the brain metabolic network in patients with WMHs.

• Journal of the Korea Concrete Institute
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• v.19 no.5
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• pp.603-611
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• 2007

Three interior slab-column connections designed by equal static moments and by different distribution of end and midspan moments were tested. Each test specimen consists of a 4.2 m square slab and a 355 mm square column stub. The slab thickness is 152 mm. Test results showed not only that flat plate systems can undergo considerable redistribution of moments from the uncracked state to final maximum capacity, but also that the distribution of moments is controlled largely by the distribution of reinforcement adopted by the designer. Tests also indicated that the punching shear strength of slabs can be affected by the redistributed moments.

• Journal of Power Electronics
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• v.1 no.1
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• pp.36-47
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• 2001

The carrier-based space vector pulse width modulation(SVPWM), which is considered as highly simple and efficient PWM technology, can be also used in multilevel inverters. The method was originally designed for the two-level inverter and developed to the diode clamped multilevel inverter structure. however it may be noted that it also cause bad switch utilization in cascaded multilevel inverter. This paper introduces an improved carrier-based SVPWM scheme, which is fully suitable for cascaded multilevel inverter topologies because it can achieve the optimized switch utilization through the redistribution of the triangular carrier waves considering leg voltage redundancies while having the advantages of the conventional carrier-based SVPWM. Using simulation and experimental results, the superior performance of new PWM method is shown.