• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.6
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• pp.593-596
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• 2015

In this paper, we design a high efficiency class E power amplifier operating at low drain bias voltage for wireless power transfers. A 13.56 MHz power amplifier is designed at drain bias voltage of 12.5 V using Si MOSFET with the breakdown voltage of 40 V. High quality-factor solenoidal inductor is designed and fabricated for use in output matching circuit to improve output power and efficiency. Input matching circuit simply consists of resistor and inductor to reduce the circuit area and improve the stability. The fabricated power amplifier shows the measured output power of 38.6 dBm with the gain of 16.6 dB and power added efficiency of 89.3 % at 13.56 MHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.99-106
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• 2001

In this paper, an 1-Watt amplifier for IMT-2000 was designed and fabricated using feedfarward method which has the highest linearity and wide bandwidth. Since feedforward is sensitive to surroundings for example heat, input power level, time and so on, adaptive controller using micro controller is adopted. We fabricated a HPA with 35 dB gain, 40 dBm of 1-dB compression point, and utilized variable attenuator and variable phase shifter using reflection type to cancel loop signal. From the measured results, the fo11owing facts were obtained, in signal loop, main carrier over 35 dB was suppressed and error signal over 30 dB is cancelled in error loop, IMD characteristics above 60 dBc were obtained.

• International Journal of Industrial Entomology and Biomaterials
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• v.37 no.1
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• pp.21-28
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• 2018

CRISPR/Cas9 gene editing system is an efficient method to mutation in a sequence specific manner. Here we report the direct transfection of the Cas9 nuclease and gene specific guide RNA can be used in BM-N cell line derived from Bombyx mori ovarian tissue to enfeeble function of endogenous gene in vitro. We have used gene editing system to negative regulation components of major signaling cascade, the Toll pathway, which controls B. mori resistance to microbe infections, such as fungi and gram positive bacteria. We demonstrate that the $I{\kappa}B-like$ protein Cactus may controls the activation of transcription factors such as Rel A and Rel B. The direct transfection of Cas9 nuclease and Cactus-specific guide-RNA complex may be used in BM-N cells to disrupt the function of endogenous genes in vitro. A mutation frequency of 30-40% was observed in the transfected cells, and various mutations caused the target region. Moreover, RT-PCR analysis revealed that Cactus gene was down regulated after these mutations. More importantly, mutation of BmCactus stimulated expression of lysozyme, moricin, and lebocin genes. These results suggest that the CRISPR/Cas9 systems are expected to efficiently induce site-specific mutations and it was possible to produce antimicrobial peptide through the gene editing.

• Clinical and Experimental Reproductive Medicine
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• v.46 no.2
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• pp.87-94
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• 2019

Objective: The primary objective of this study was to compare clinical pregnancy rates in intrauterine insemination (IUI) treatment cycles with transabdominal ultrasound guidance during intrauterine catheter insemination (US-IUI) versus the "blind method" IUI without ultrasound guidance (BM-IUI). The secondary objective was to compare whether US-IUI had better patient tolerability and whether US-IUI made the insemination procedure easier for the clinician to perform compared to BM-IUI. Methods: This was a randomized controlled trial done at the Reproductive Medicine Unit of General Hospital Kuala Lumpur, Malaysia. We included women aged between 25 and 40 years who underwent an IUI treatment cycle with follicle-stimulating hormone injections for controlled ovarian stimulation. Results: A total of 130 patients were recruited for our study. The US-IUI group had 70 patients and the BM-IUI group had 60 patients. The clinical pregnancy rate was 10% in both groups (p> 0.995) and there were no significant difference between the groups for patient tolerability assessed by scores on a pain visual analog scale (p= 0.175) or level of difficulty for the clinician (p> 0.995). The multivariate analysis further showed no significant increase in the clinical pregnancy rate (adjusted odds ratio, 1.07; 95% confidence interval, 0.85-1.34; p= 0.558) in the US-IUI group compared to the BM-IUI group even after adjusting for potential covariates. Conclusion: The conventional blind method for intrauterine catheter insemination is recommended for patients undergoing IUI treatment. The use of ultrasound during the insemination procedure increased the need for trained personnel to perform ultrasonography and increased the cost, but added no extra benefits for patients or clinicians.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.37-40
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• 2003

The 1.63㎓, 2.33㎓ dual-band PLL frequency synthesizer has been developed for applications to the miniature repeater. The miniature dual-band repeater will be used at shopping mall, basements and underground parking lots. The in-loop 1.63㎓, 2.33㎓ dual-band PLL frequency synthesizer has been developed by designing Si BJT VCO and PLL loop circuits with Colpitts. The prototype of 1.63㎓, 2.33㎓ dual-band PLL frequency synthesizer of size 19${\times}$19${\times}$8(mm) has shown operating frequencies of 1.63㎓, 2.33㎓ ranges, RF output of 1dBm(PCS), 1dBm(IMT-2000), phase noise of -100 dBc/Hz(PCS), -95dBc/Hz(IMT-2000) at 10KHz offset, harmonics suppression of -24dB c(PCS), -15dBc(IMT-2000).

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.89-92
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• 2008

CMOS 기반의 고주파 집적회로에서는 높은 이득과 출력을 얻기 위하여 인덕터와 같은 수동소자를 사용한다. 그러나 수동소자를 사용하게 되면 넓은 면적을 차지하기 때문에 회로의 크기를 증가시키는 단점을 갖는다. 본 논문에서는 PMOS 를 기반으로 구현한 active inductor 를 적용하여 회로의 면적을 줄일 수 있으며, 기존의 주파수 변환기와 동등한 선형 특성을 갖는 상향 주파수 변환기를 설계하였다. 인덕터를 적용한 상향 주파수 변환기의 OIP3 ($3^{rd}$ Output Intercept Point)는 1.3 dBm 을 가지며, 제안한 상향 주파수 변환기의 OIP3 는 0.8 dBm 으로 동등한 선형 특성을 보이며, layout 상에서 회로의 면적을 40 % 이상 감소하는 특성의 선형 송신기용 주파수 변환기를 설계 분석하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.105
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• pp.101-109
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• 2006

A broadband, DC to 40 GHz 5-bit MMIC digital attenuator has been developed. The ultra broadband attenuator has been achieved by adding transmission lines in the conventional Switched-T attenuator and optimizing the transmission line parameters. Momentum simulation was performed in design for accurate performance prediction at high frequencies and Monte Carlo analysis was applied to verify the performance stability against the MMIC process variation. The attenuator has been fabricated with $0.15\;{\mu}m$ GaAs pHEMT process. This attenuator has 1 dB resolution and 23 dB dynamic ranges. High attenuation accuracy has been achieved over all attenuation ranges and 40 GHz bandwidth with the reference state insertion loss of less than 6 dB at 20 GHz. The input and output return losses of the attenuator are better than 14 dB over all attenuation states and frequencies. The measured IIP3 of the attenuator is 33 dBm.

• Journal of IKEEE
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• v.26 no.4
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• pp.722-727
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• 2022

In this paper, we present the design and characterization of a power amplifier (PA) monolithic microwave integrated circuit (MMIC) in the X-band. The device is designed using a 0.25 ㎛ gate length AlGaN/GaN high electron mobility transistor (HEMT) on SiC process. The developed X-band AlGaN/GaN power amplifier MMIC achieves small signal gain of over 21.6 dB and output power more than 46.11 dBm (40.83 W) in the entire band of 9 GHz to 10 GHz. Its power added efficiency (PAE) is 43.09% ~ 44.47% and the chip dimensions are 3.6 mm × 4.3 mm. The generated output power density is 2.69 W/mm². It seems that the developed AlGaN/GaN power amplifier MMIC could be applicable to various X-band radar systems operating X-band.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.1
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• pp.35-43
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• 2022

In this paper, a study was conducted to produce 20W by combining a 10W MMIC and raising the unit power amplifier to 100W SSPA by combining the 8-way spatial coupler. SSPA requires low-loss, high-efficiency coupling techniques to meet high output with the output of a single element relatively low compared to TWTA. Designed and produced in this paper, the SSPA was manufactured as a 100W SSPA by mounting eight 20W high-power amplification modules in an 8-way spatial coupler with a reflection loss of 20dB or more and an excellent coupling efficiency of 94% or more. When -10dBm was applied, it was 112.2~169.8W at 20kHz 20%, 125.9~173.8W at 400kHz 40%, 117.5~162.2W at 800kHz 40%, showing performance of over 60dB and over 100W in all three PRF conditions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.839-846
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• 2007

In this paper, the first attempt to design a novel structure of dual-band feedforward linear power amplifier(FFW LPA) was presented. Up to now, primary technical difficulty has been the extension of the conventional signal canceller to the dual-band operation. Therefore, we propose the design technique of the dual-band equal group delayed carrier canceller, the dual-band equal group delayed intermodulation distortion(IMD) canceller and the dual-band FFW LPA. The operation frequency bands of the implemented dual-band FFW LPA are digital cellular($f_0=880$ MHz) and IMT-2000($f_0=2.14$ GHz) band, which are separated about 1.26 GHz. With the high power amplifier of 120 W PEP for commercial base-station application, IMD cancellation loop shows 20.45 dB and 25.04 dB loop suppression at each band of operation for 100 MHz. From the adjacent channel leakage ratio(ACLR) measurement with CDMA IS-95A 4FA and WCDMA 4FA signal, we obtained 16.52 dB improvement at the average output power of 41.5 dBm for digital cellular band, and 18.59 dB improvement at the average output power of 40 dBm for IMT-2000 band simultaneously.