• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.11
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• pp.130-137
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• 2013

This paper presents analog front-end(AFE) circuits for bio-potential measurement. The proposed AFE is composed of IA(instrument amplifier), BPF(band-pass filter), VGA(variable gain amplifier) and SAR(successive approximation register) type ADC. The low gm(LGM) circuits with current division technique and Miller capacitance with high gain amplifier enable IA to implement on-chip AC-coupling without external passive components. Spilt capacitor array with capacitor division technique and asynchronous control make the 12-b ADC with low power consumption and small die area. The total current consumption of proposed AFE is 6.3uA at 1.8V.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.10
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• pp.22-29
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• 1998

In this paper, an 10 bit current-mode CMOS A/D converter with a current predictor is designed with a CMOS process to be integrated into a portable image signal processing system. A current predictor let the number of comparator reduce to 70 percent compared with the two step flash architecture. The current magnitude of current reference is reduced to 68 percent with a modular current reference. The designed 10 bit Low-power current-mode CMOS A/D converter with a current predictor is simulated with HSPICE using 0.6$\mu\textrm{m}$ N-well single-poly triple-metal CMOS process parameters. It results in a conversion rate of 10MSamples/s. A power consumption is measured to be 94.4mW at single +5V supply voltage. The 10 bit A/D converter fabricated using the same process occupies the chip area of 1.8mm x 2.4mm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.66-69
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• 2016

In this paper, we suggests a Ka-band LNB considering next-generation UHD satellite TVRO. Since Ka-band has grater attenuation than Ku-band in atmosphere, we designed the low-noise down-converter to improve receiving sensitivity and to extend a dynamic range of receiver. It aims to compensate a quality of ultra high definition transmission signal for rainfall. The low-noise block diagram consists of a three-staged amplifier (LNA), band-pass filter for deleting image (BPF), mixer and IF when considering nonlinear characteristics in the receiver RF front end module. Also, we showed a LNB through optimization processes affecting dynamic range directly in receiver FEM. Asa resuly of experiment, the gain of low-noise down-converter show between 58.5dB and 60.7dB, the noise figure has a high characteristic as 1.38dB. Finally, the phase noise of local oscillator is -63.10dBc at 100MHz offset frequency.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.3
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• pp.191-198
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• 2015

Noise propagated through the ventilation openings of enclosures is actively controlled using an FIR filter. The enclosures considered in this paper are used for isolating noise due to machinery. This method is of limited use because of the ventilation openings through which most of noise is propagated. Feedforward control strategy is incorporated to minimize the acoustic power propagated through the openings. For the real-time implementation, although it is numerical study, the controller is implemented using an FIR filter. The acoustic transfer functions of the pressure on the openings of the enclosure to the primary source and to the secondary source are numerically calculated using the boundary element method. The performance analysis of the active control is conducted with the time-domain simulation using Matlab Simulink.

• Journal of Chest Surgery
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• v.39 no.7 s.264
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• pp.505-510
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• 2006

Background: Small animal cardiopulmonary bypass (CPB) model would be a valuable tool for investigating path-ophysiological and therapeutic strategies on bypass. The main advantages of a small animal model include the reduced cost and time, and the fact that it does not require a full scale operating environment. However the rat CPB models have a number of technical limitations. Effective maintenance and control of core temperature by a heat exchanger is among them. The purpose of this study is to confirm the effect of rectal temperature maintenance using a heat exchanger of cardioplegia system in cardiopulmonary bypass model for rats. Material and Method: The miniature circuit consisted of a reservoir, heat exchanger, membrane oxygenator, roller pump, and static priming volume was 40 cc, Ten male Sprague-Dawley rats (mean weight 530 gram) were divided into two groups, and heat exchanger (HE) group was subjected to CPB with HE from a cardioplegia system, and control group was subjected to CPB with warm water circulating around the reservoir. Partial CPB was conducted at a flow rate of 40 mg/kg/min for 20 min after venous cannulation (via the internal juglar vein) and arterial cannulation (via the femoral artery). Rectal temperature were measured after anesthetic induction, a ter cannulation, 5, 10, 15, 20 min after CPB. Arterial blood gas with hematocrit was also analysed, 5 and 15 min after CPB. Result: Rectal temperature change differed between the two groups (p<0.01). The temperatures of HE group were well maintained during CPB, whereas control group was under progressive hypothermia, Rectal temperature 20 min after CPB was $36.16{\pm}0.32^{\circ}C$ in the HE group and $34.22{\pm}0.36^{\circ}C$ in the control group. Conclusion: We confirmed the effect of rectal temperature maintenance using a heat exchanger of cardioplegia system in cardiopulmonary bypass model for rats. This model would be a valuable tool for further use in hypothermic CPB experiment in rats.

• Clinical and Experimental Pediatrics
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• v.52 no.1
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• pp.44-49
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• 2009

Purpose : Early surfactant treatment and minimal ventilation, bronchopulmonary dysplasia needed prolonged oxygen supplement is a problem. This study aimed to report the effects of early surfactant treatment and minimal ventilation on the prevention of bronchopulmonary dysplasia in respiratory distress syndrome. Methods : We retrospectively studied 139 premature newborn infants (gestational age, 36 weeks; birth weight, 1,500 gm) admitted to the neonatal intensive care unit of Daegu Fatima Hospital between January 2001 and December 2006. We analyzed the occurrence of bronchopulmonary dysplasia with respect to ventilator care and surfactant treatment. Results : The incidence of bronchopulmonary dysplasia was significantly higher with prolonged ventilator care, moderate to severe respiratory distress syndrome, and low Apgar score (P<0.001). Despite early surfactant treatment and minimal ventilation, mild bronchopulmonary dysplasia occurs in a considerable number of patients with mild respiratory distress syndrome. The patient group with low Apgar scores required ventilator care for a prolonged period (P=0.020). Conclusion : Early surfactant treatment and minimal ventilation shortens the duration of ventilator care; however, the preventive effects on bronchopulmonary dysplasia are limited. Therefore, not only early surfactant treatment and minimal ventilation but also appropriate management in the delivery room is essential.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.6
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• pp.1143-1150
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• 2001

In this paper, we designed a downconverter for K-band satellite multipoint distribution service(SMDS). The designed downconverter consists of a low noise amplifiers, bandpass filter, stable local oscillator, drain mixer and If Amplifiers. Low noise amplifiers show 28㏈ gain and 1.5㏈ noise figure in the frequency range of 19.2㎓~20.2㎓, and a band pass filter has a -l㏈ insertion loss, and 18.25㎓ Stable local oscillator which is dielectric resonant oscillation, We obtained that the output power of the 18.25㎓ oscillation frequency is 0.5㏈m and the phase noise is the -84.67㏈c at 10KHz offset frequency. With the input RF signal the 19.2㎓~20.2㎓, conversion gain of the drain mixer shows 5㏈ at the Intermediate frequency range of 950MHz~1950MHz. We have proved that the designed downconverter satisfied the specification of a K-band satellite multipoint distribution service and it can be applied to the satellite internet receiver.

• The Transactions of the Korea Information Processing Society
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• v.2 no.1
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• pp.66-74
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• 1995

A 8-bit 15MHz CMOS subranging Analog-to-Digital converter for high-speed, low-power consumption applications is described. Subranging, 2 step flash, A/D converter used a new resistor string and a simple comparator architecture for the low power consumption and small chip area. Comparator exhibites 80dB loop gain, 50MHz conversion speed, 0.5mV offset and maximum error of voltage divider was 1mV. This Analog-to-Digital converter has been designed and fabricated in 1.2 m N-well CMOS technology. It consumed 150mW power at ＋5/-5V supply and delayed 65ns. The proposed Analog-to-Digital converter seems suitable for high- speed, low-power consumption, small area applications and one-chip mixed Analog- Digital system. Simulations are performed with PSPICE and a fabricated chip is tested.

• Clinical and Experimental Pediatrics
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• v.48 no.10
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• pp.1096-1101
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• 2005

Purpose : Recently, early surfactant replacement and tidal volume based gentle ventilation has been a fundamental treatment of respiratory distress syndrome(RDS). The aims of this study were to survey the changes in ventilator care duration and rate of complication in RDS groups. Methods : We performed a retrospective study of 255 newborn infants less than 1,500 g admitted to the neonatal intensive care unit(NICU) and discharged from January 1999 to December 2003. 141 of 255 newborn infants were RDS groups that required invasive management, such as endotracheal intubation, surfactant replacement and assisted ventilation. We analyzed epidemiologic data to study the changes in ventilator care duration and outcome of RDS groups. Results : Of 141 RDS groups, 135 were mild to moderate RDS groups and only 6 were severe RDS groups. 24(17.8%) of 135 mild to moderate RDS groups and 3(50%) of 6 severe RDS groups were antenatal no use of maternal dexamethasone. 127(90.1%) of 141 RDS groups underwent replacement of surfactant during 3 hours after birth. 121(85.9%) weaned within 48 hours. Conclusion : Our study shows a decreased frequency of severe RDS by a antenatal use of maternal dexamethasone and decreased duration of ventilator care by early surfactant replacement and gentle ventilation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1276-1293
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• 1993

A numerical and experimental flow visualization study of the louvered fin array, commonly used in a compact heat exchanger was performed. The flow structure which was obtained by using a finite difference method, was compared with an experimental result. The experimental flow visualization was performed by using a dye injection technique with 13:1 scale model. The effects of Reynolds number and fin geometries on flow structure and heat transfer were examined.