• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.6 s.336
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• pp.59-66
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• 2005

CMOS LC VCO for tri-bind wireless LAN applications was designed in 1.8V 0.18$\mu$m CMOS process. PMOS transistors were chosen for VCO core to reduce flicker noise. The possible operation was verified for 5.8GHz band (5.725$\~$5.825GHz), 5.2GHz band (5.150$\~$5.325GHz), and 2.4GHz band (2.412$\~$2.484GHz) using the switchable L-C resonators. To linearize its frequency-voltage gain (Kvco), optimized multiple MOS varactor biasing technique was used for capacitance linearization and PLL stability improvement. VCO core consumed 2mA current and $570{\mu}m{\times}600{\mu}m$ die area. The phase noise was lower than -110dBc/Hz at 1MHz offset for tri-band frequencies.

• The Journal of Korean Obstetrics and Gynecology
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• v.32 no.1
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• pp.1-14
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• 2019

Objectives: This study was designed to investigate the effect of Bombycis corpus on reproductive dysfunction caused by aging. Methods: The experimental group was divided into three groups: a control group consisting of 8-week-old male ICR mice without any treatment, An aging-elicited group (AE group) consisting of 50-week-old ICR male mice without any treatment, and a Bombycis corpus treatment group (BC group) consisting of 50-week-old ICR male mice with treatment Bombycis corpus extract (0.78 g/kg/day) for 6 months. After 6 months, histochemistry and immunohistochemistry of the testis were performed to investigate the effects of Bombycis corpus on the reproductive dysfunction caused by aging. Results: In the first step, Bombycis corpus increased spermatogenesis and distribution of sertoli cells in the seminiferous tubule, increased BrdU positive reaction in the spermatogonium at the basal part of the seminiferous tubule, and decreased the apoptosis of Sertoli cells in the seminiferous tubule. In addition, Bombycis corpus increased AR positive in Sertoli cells and $17{\beta}-HSD$ positive in leydig cells. Finally, Bombycis corpus decreased 8-OHdG positivite reaction in the spermatids of the seminiferous lumen, caspase-3 positivity in leydig cells, and HDAC1 positivite reaction in sertoli cells. Conclusions: These results suggest that Bombycis corpus increases spermatogenesis, decreases apoptosis of leydig cells and Sertoli cells, increases the production and action of testosterone in the testis, and inhibits DNA damages and DNA transcripts decrease in the testis, Thereby improving reproductive dysfunction caused by aging.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.3
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• pp.378-386
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• 2017

A return-to-zero (RZ) digital-to-analog converter (DAC) with a tri-state switching scheme is proposed in this paper. The proposed scheme provides a triple weight output for RZ operation by using a conventional differential current switch and simple pseudo-differential F/Fs. The RZ function is realized with only two additional transistors in each F/F cell, which results in a power dissipation increase of less than 5%. To verify the performance of the proposed method, a 10-bit RZ DAC is fabricated using standard 180-nm CMOS technology. Measured results show that the worst SFDR performances are 60 dBc and 55 dBc in the 1st and 2nd Nyquist bands, respectively, when operating at 650 MHz clock frequency. The total power consumption is 64 mW, and the active area occupies $0.25mm^2$.

• Proceedings of the KSAR Conference
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• 2001.03a
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• pp.61-61
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• 2001

The main goal of this study was to produce transgenic piglets by the method of injection of sperm-mediated exogenous DNA. Spermatozoa (1$\times$106 sperm of final concentration) obtained from caudal epididymis were mixed with pBC1-hEPO (20 ng/${mu}ell$) or pcDNA3 LAC Z (20 ng/${mu}ell$), and followed by electroporation (500 V, 25 ㎌). Matured oocytes having the first polar body and dense cytoplasm were selected and centrifuged at 12,000g for 6 min. After sperm injection, the oocytes were activated electrically (1.7 ㎸/cm, 30 $\mu$ sec, single pulse) in 0.3 M mannitol solution. Eggs injected sperm were cultured in NCSU 23 medium (0.4% BSA) at 39$^{\circ}C$, 5% $CO_2$ in air for 192 h. This study were comprised 3 experiments. Experiment 1 compared the developmental efficiencies between the sperm-injected oocytes (Group 1) and further activated electrically (Group 2). Experiment 2 compared the expression of pcDNA3 LAC Z in the embryos produced by Group 1 and Group 2. Finally, experiment 3 carried out transfer of embryos (1-8 cell stage) transfected with pBC1 -hEPO into surrogate recipients synchronized by injection of combination of PG600 with hCG. The rates of cleavage and development into blastocyst stage in Group 2 were significantly higher than those of Group 1 (71.3% and 28.1% vs. 43.3% and 10.3%, respectively, p<0.05). Thirty (24.2%) out of 124 embryos analyzed in Group 2 were positive by X-gal. Similarly, in Group 1, 16.3% (8/49) were positive. After transfer of 789 embryos to 7 recipient gilts, three out of them examined by ultrasound became pregnant. One recipient is in day 50 pregnancy. On day 54 of gestation, two were carried out uterotomy in order to confirm the pregnancy One had 7 and another had 2 fetuses. We conclude that injection of sperm-mediated gene transfer will be used as a valuable tool for the production of transgenic piglets.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.413-414
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• 2008

A 2.4 GHz low phase noise fully integrated LC voltage-controlled oscillator (VCO) in $0.18\;{\mu}m$ CMOS technology is presented in this paper. The VCO is optimized based on phase noise reduction. The design of the VCO uses differential varactors which are adopted for symmetry of the circuit, and consider AM-PM conversion due to a cross-coupled pair. The VCO is designed to draw 3 mA from 1.8 V supply voltage. Simulated phase noise is -137.3 dBc/Hz at 3 MHz offset. The tuning range is found to be 300 MHz range from 2.3 GHz to 2.6 GHz.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.890-893
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• 2003

In this paper, we have designed the fractional-N frequency synthesizer for bluetooth system using 0.35-um CMOS technology and 3.3-V single power supply. The designed synthesizer consist of phase-frequency detector (PFD), charge pump, loop filter, voltage controlled oscillator (VCO), frequency divider, and sigma-delta modulator. A dead zone free PFD is used and a modified charge pump having active cascode transistors is used. A Multi-modulus prescaler having CML D flip-flop is used and VCO having a tuning range from 746 MHz to 2.632 GHz at 3.3 V power supply is used. Total power dissipation is 32 mW and phase noise is -118 dBc/Hz at 1 MHz offset.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.11
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• pp.94-100
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• 2014

In this paper, a design of low power Current-Reuse Voltage Controlled Oscillator (VCO) which has wide tuning range about 1.95 GHz ~ 3.15 GHz is presented. Class-C type is applied to improve phase noise and 2-Step Auto Amplitude Calibration (AAC) is used for minimizing the imbalance of differential VCO output voltage which is main issue of Current-Reuse VCO. The mismatch of differential VCO output voltage is presented about 1.5mV ~ 4.5mV. This mismatch is within 0.6 % compared with VCO output voltage. Proposed Current-Reuse VCO is designed using CMOS $0.13{\mu}m$ process. Supply voltage is 1.2 V and current consumption is 2.6 mA at center frequency. The phase noise is -116.267 dBc/Hz at 2.3GHz VCO frequency at 1MHz offset. The layout size is $720{\times}580{\mu}m^2$.

• Journal of the Korean Society for Library and Information Science
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• v.36 no.1
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• pp.259-296
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• 2002

The purpose of this Study is on the Foundation of the Great Library of Alexandria. The foundation of the Great Library at Alexandria was a natural consequence of the enormous growth for book production and the book trade, in which Athens had taken the lead from the fifth century BC. onward. Alexandria Library(BC. 290${\sim}$AD. 642) is the first to house the collection of comprehensive knowledge on the world in human history. The library is the birthplace of mainstream of Greek civilization and played a pivotal role in academic world. The purpose of this research could be summarized as fellows; The purpose of this research is 1) considering establishment, development and decline of Alexandria Library, 2) researching the historical foundation background of Museum and Library, 3) investigating effect on the cataloging history 4) reviewing the value of the Library’s stock of books. This Study employs historical research methods mainly through literature review and mutual comparative methods of many researcher’s studies.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.2
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• pp.301-306
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• 2005

In this paper, a gain-boosting charge pump(CP) and a latch type voltage controlled oscillato.(VCO) with voltage controlled resistor(VCR) were proposed. The gain-boosting CP achieves good .current matching of less than 11$mu$V voltage difference between 43$mu$V and 32$mu$V in its output range from 0.8V to 2.3V. The VCO with VCR shows good linear characteristics over the range from 1V to 3V. The fabricated VCO exhibits -108dBc/Hz phase noise at a 100kHz and is comparable to that of the integrated LC-tank oscillator. The phase locked loop(PLL) with new circuits was simulated in a 0.35$mu$m CMOS process and showed 150$mu$s locking time.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.72-80
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• 1996

This paper presetns the development of a SSPA operating at KU-band(14~14.5 GHz) in order of replace TWTA used in the terrestria transponder of a satellite communication. The driving stage of SSPA uses internally matched 2W, 4W, 8W FET and the power stage is coupled with two internally matched 8W FET by branch-line cominer. The SSPA is fabricated with oth the RF circuit and the bias circuitry operating temperature compensation, regulation and sequence on aluminum housing. The SSPA testing resutls implemented in this way show 24.8$\pm$1dB small-signal gain, 41dBm P1dB power, a typical two tone C/IM3, -33dBc with single carrier backed off 6dB from p1dB, and gain stability over temeprature (-30~50)$\pm$1dB.