• Smart Structures and Systems
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• v.23 no.2
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• pp.173-184
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• 2019

The main objective of this study is to evaluate the true fracture energy and monitor the damage progression in steel fibre reinforced concrete (SFRC) specimens using acoustic emission (AE) features. Four point bending test is carried out using pre-notched plain and fibre reinforced (0.5% and 1% volume fraction) - concrete under monotonic loading. AE sensors are affixed at different locations of the specimens and AE parameters such as rise time, AE energy, hits, counts, amplitude and duration etc. are obtained. Using the captured and processed AE event data, fracture process zone is identified and the true fracture energy is evaluated. The AE data is also employed for tracing the damage progression in plain and fibre reinforced concrete, using both parametric- and signal- based techniques. Hilbert - Huang transform (HHT) is used in signal based processing for evaluating instantaneous frequency of the acoustic events. It is found that the appropriately processed and carefully analyzed acoustic data is capable of providing vital information on progression of damage on different types of concrete.

• Toxicological Research
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• v.33 no.4
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• pp.343-350
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• 2017

Lamivudine belongs to the set of antiviral agents effective against hepatitis B virus infection. Given case reports on liver injuries after certain antiviral agent treatments, this study examined the effects of lamivudine on alanine aminotransferase (ALT) and total bilirubin (TB) using a medical system database. A total of 1,321 patients taking lamivudine alone or with others were evaluated using laboratory hits in an electronic medical system at Seoul National University Hospital from 2005 through 2011. The patients were grouped according to prior ALT results: G#1, ALT < 40 IU/L; G#2, 40 IU/L ${\leq}$ ALT < 120 IU/L; G#3, 120 IU/L ${\leq}$ ALT < 240 IU/L; and G#4, ALT ${\geq}$ 240 IU/L. In G#1 and G#2 patients, lamivudine or adefovir treatment decreased ALT and TB compared to prior values. In G#3 and G#4 patients with three times the upper limit of normal (ULN) ${\leq}$ ALT < 15 times the ULN, both ALT and TB were decreased after treatment with lamivudine alone, or adefovir following lamivudine therapy, indicating that lamivudine therapy ameliorated liver functions. However, in G#4 patients who experienced severely advanced hepatitis (ALT ${\geq}$ 15 times the ULN, or ${\geq}$ 600 IU/L), lamivudine augmented TBmax ($6.3{\rightarrow}13.3mg/dL$) despite a slight improvement in ALT ($839{\rightarrow}783IU/L$), indicative of exacerbation of bilirubinemia. Patients who used adefovir after lamivudine also showed a high incidence of hyperbilirubinemia when they experienced severely advanced hepatitis. Treatment with adefovir alone did not show the effect. In conclusion, lamivudine may increase the risk of hyperbilirubinemia in patients with severely advanced hepatitis, implying that caution should be exercised when using lamivudine therapy in certain patient populations.

• Korean Journal of Cognitive Science
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• v.26 no.3
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• pp.357-375
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• 2015

In our daily life, the probability of target prevalence in visual search varies from very low to high. However, most laboratory studies of visual search used a fixed probability of target prevalence at 50%. The present study examined the properties of information processing during visual search where the probability of target prevalence was manipulated to vary from low (20%), medium (50%), to high (80%). The search items were made of simple shape stimuli, and search accuracy, signal detection measures, and reaction times (RTs) were analyzed for characterizing the effect of target prevalence on the information processing strategies for visual search. The analyses showed that the rates of misses increased whereas those of false alarms decreased in the search condition of low target prevalence, whereas the pattern was reversed in the high prevalence condition. Signal detection measures revealed that the target prevalence shifted response criterion (c) without affecting sensitivity (d'). In addition, RTs for correct rejection responses in the target-absent trials became delayed as the prevalence increased, whereas those for hits in the target-present trials were relatively constant regardless of the prevalence. The RT delay in the target-absent trials indicates that increased target prevalence made the 'quitting threshold' for search termination more conservative. These results support an account that the target prevalence effect in visual search arises from a shift of decision criteria and the subsequent changes in search information processing, while rejecting the account of a speed-accuracy tradeoff.