• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.4
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• pp.323-332
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• 2009

In this paper, we introduce a modified short-circuited stub bandpass filter suitable for ultra-wideband(UWB) applications utilizing low temperature co-fired ceramic(LTCC) technology. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate($\varepsilon_r$ = 40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825 GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter has been measured with an insertion loss less than 1.0 dB and return loss better than 10 dB in the pass bands. A bandwidth ratio of 109.49 % has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are $4{\times}8{\times}0.57\;mm^3$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.60-68
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• 2016

This paper presents a 6~18 GHz 7-bit digital-controlled attenuator. The proposed attenuator is based on switched-T architecture, but no inductor is used for minimum chip size. The designed attenuator was fabricated using $0.18{\mu}m$ CMOS process, and characterized using on-wafer testing setup. The resolution(minimum attenuation step) and the maximum attenuation range of the attenuator were measured to be 0.22 dB and 28 dB, respectively. The measured RMS attenuation error and the RMS phase error for 6~18 GHz were less than 0.26 dB and $3.2^{\circ}$, respectively. The reference state insertion loss was less than 12.4 dB at 6~18 GHz. The measured input and output return losses were better than 9.4 dB over all frequencies and attenuation states. The chip size is $0.11mm^2$ excluding pads.

• Journal of The Korean Dental Society of Anesthesiology
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• v.12 no.1
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• pp.45-50
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• 2012

The Fontan operation is a heart operation used to treat complex congenital heart defects like tricuspid atresia, hypoplastic left heart syndrome, pulmonary atresia and single ventricle. A single ventricle is dedicated to pumping oxygenated blood to the systemic circulation and the entire systemic venous return reaches the pulmonary arterial system without the direct influence of a pumping chamber. In the patient with Fontan operation, it is important to achieve adequate pulmonary blood flow and cardiac output in anesthetic management. In this case, a 10-year-old boy (19.6 kg, 114 cm) with cleft palate, cerebral palsy and severe mental retardation, who underwent a Fontan operation when he was 4 years old, was presented for deep sedation. Because he was suffering from eating disorder with cleft palate, the orthodontist and the plastic surgeon planned to insert intraoral orthodontic device before cleft palate repair. But it was impossible to open his mouth for alginate impression procedure. After careful pre-anesthesia evaluation we planned to administer deep sedation with propofol infusion. After Intravenous catheter insertion, we started propofol intravenous infusion with the formula of a loading dose of 1.0 mg/kg followed by an infusion rate of 6.0 mg/kg/hr with syringe pump. His blood pressure was remained around 80/40 mmHg after loss of consciousness, but he could not maintain his airway patent. So we lowered the infusion rate to 3.0 mg/kg/hr, immediately. The oxygen saturation was maintained above 95% with nasal oxygen supply, and blood pressure was maintained around 100-80/60-40 mmHg. After the sedation of 110 minutes with propofol (the infusion rate to 3.0-5.0 mg/kg/hr), he fully regained consciousness, and was discharged without complication after 1 hour observation. In case of post-Fontan patient, intravenous deep sedation with propofol was safe and effective method of behavioral management during dental treatment.