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In the voltage-source-converter-based dc system, the short-circuit current increases rapidly due to neighborhood dc-link capacitance. The protection system using a high-speed fuse has been applied in the industry to protect before the current freewheeling that ruins a semiconductor device. For proper protection system design, the capacitor-discharge I2t must be analyzed and set higher than the melting I2t of the fuse by securing sufficient capacitance. However, due to the implicit characteristics of the I2t function, it is difficult to calculate the required capacitance directly considering unknown fault resistance. In this article, the normalized I2t map of capacitor-discharge is presented as a calculation reference. After calculating the base values, the normalized I2t value can be calculated easily from the map without complicated formula. Since it is expressed as a function of the damping factor (half of the normalized resistance) and normalized capacitor's voltage, it helps I2t design with the range of fault resistance and voltage drop simultaneously. The proposed normalization and its result were verified through the experimental tests under various fault resistance. [ABSTRACT FROM AUTHOR]

Background: We performed a prospective study to evaluate and compare the effectiveness of postoperative pain control methods after bone surgery in the foot and ankle.Methods: Among the patients who underwent foot and ankle surgery from June 2014 to September 2015 with an ultrasound-guided nerve block, 84 patients who fully completed a postoperative pain survey were enrolled. An opioid patch (fentanyl patch, 25mg) was applied in group A (30 patients). Diluted anesthetic (0.2% ropivacaine, 30ml) was injected into the sciatic nerve once, about 12h after the preoperative nerve block, in group B (27 patients). Periodic intramuscular injection of an analgesic (ketorolac [Tarasyn], 30mg) was performed in group C (27 patients). The visual analogue scale (VAS) pain scores at 6, 12, 18, 24, and 48h after surgery were checked, and the complications of all methods were monitored.Results: The mean VAS pain score was lower in group B, with a statistically significant difference (P<.05) between groups A, B, and C at 12 and 18h after surgery. Four patients in group A experienced nausea and vomiting; however, no other patients complained of any complications or adverse effects.Conclusion: The ultrasound-guided injection of a diluted anesthetic into the sciatic nerve seemed to be the most useful method for controlling pain in the acute phase after bone surgery in the foot and ankle. The injection of the diluted anesthetic once on the evening of the day of surgery resulted in less postoperative pain in the patients.Level Of Evidence: II. [ABSTRACT FROM AUTHOR]