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양진호,Andrea McDowell,서호찬,김성원,민택기,지영구,최영우,박해심,편복양,김윤근 대한천식알레르기학회 2020 Allergy, Asthma & Immunology Research Vol.12 No.5
Purpose: Associations between a wide variety of diseases and the microbiome have been extensively verified. Recently, there has been a rising interest in the role the microbiome plays in atopic dermatitis (AD). Furthermore, metagenomic analysis of microbe-derived extracellular vesicles (EVs) has revealed the importance and relevance of microbial EVs in human health. Methods: We compared the diversity and proportion of microbial EVs in the sera of 24 AD patients and 49 healthy controls, and developed a diagnostic model. After separating microbial EVs from serum, we specifically targeted the V3–V4 hypervariable regions of the 16S rDNA gene for amplification and subsequent sequencing. Results: Alpha and beta diversity between controls and AD patients both differed, but only the difference in beta diversity was significant. Proteobacteria, Firmicutes, and Bacteroidetes were the dominant phyla in healthy controls and AD patients, accounting for over 85% of the total serum bacterial EVs. Also, Proteobacteria, Firmicutes, Actinobacteria, Verrucomicrobia, and Cyanobacteria relative abundances were significantly different between the AD and control groups. At the genus level, the proportions of Escherichia-Shigella, Acinetobacter, Pseudomonas, and Enterococcus were drastically altered between the AD and control groups. AD diagnostic models developed using biomarkers selected on the basis of linear discriminant analysis effect size from the class to genus levels all yielded area under the receiver operating characteristic curve, sensitivity, specificity, and accuracy of value 1.00. Conclusions: In summary, microbial EVs demonstrated the potential in their use as novel biomarkers for AD diagnosis. Therefore, future work should investigate larger case and control groups with cross-sectional or longitudinal clinical data to explore the utility and validity of serum microbiota EV-based AD diagnosis.
Ku 대역 위성통신용 5 W GaN MMIC 전력증폭기
김성형,진일비,양영구 한국전자파학회 2023 한국전자파학회논문지 Vol.34 No.11
본 논문에서는 150-nm GaN-HEMT 공정을 사용하여 Ku 대역 3-stage MMIC 전력증폭기를 설계하였다. 출력단에서 high pass 구조를 사용하여 회로의 크기를 줄이고 구동 증폭단에서 높은 부하 임피던스를 선택함으로써 높은 효율을 얻었다. 0.5 ms 주기의 10 % duty cycle 펄스 CW 신호를 사용하여 전력증폭기를 측정한 결과 13∼16 GHz 대역에서 포화전력37∼38 dBm, 34∼41 %의 power added efficiency(PAE)와 26∼30 dB의 전력이득 측정결과를 보인다. 제작된 전력증폭기의크기는 3.6×1.1 mm2이며 위성통신용 모듈의 송신부에 사용하기 적합하다.
A VLSI Design for Digital Pre-distortion with Pipelined CORDIC Processors
박종강,문준영,김경훈,양영구,김종태 대한전자공학회 2014 Journal of semiconductor technology and science Vol.14 No.6
In a wireless communications system, a pre-distorter is often used to compensate for the nonlinear distortions that result from operating a power amplifier near the saturation region, thereby improving system performance and increasing the spectral efficiency for the communication channels. This paper presents a new VLSI design for the polynomial digital pre-distorter (DPD). The proposed DPD uses a Coordinate Rotation Digital Computing (CORDIC) processor and a PD process with a fully-pipelined architecture. Due to its simple and regular structure, it can be a competitive design when compared to existing polynomial-type and approximated DPDs. Implementing a fifth-order distorter with the proposed design requires only 43,000 logic gates in a 0.35 μm CMOS standard cell library.
부하에 의한 출력 변화가 둔감한 6.78 MHz Class E 전력증폭기 설계
임성헌,배순철,최재혁,양영구 한국전자파학회 2022 한국전자파학회논문지 Vol.33 No.8
본 논문에서는 λ/4 임피던스 변환기를 이용하여 Class E 전력 증폭기 2개를 Doherty 전력 증폭기 구조처럼 연결하여6.78 MHz에서 부하에 의한 출력 전력의 변화를 줄이는 증폭기 구조를 설계하였다. 출력 임피던스가 낮게 설계된 Class E 전력 증폭기와 이 증폭기에 λ/4 임피던스 변환기를 추가하여 출력 임피던스가 높고, 90° 위상 차이가 나는 Class E 전력 증폭기를 single-ended로 부하에 연결하였다. 각 전력 증폭기는 FAIRCHILD SEMICONDUCTOR사의 FDMC86248를동일하게 사용하여 효율이 최대인 부하 지점에서 동일한 출력을 내고 부하가 변할 때 하나의 증폭기는 출력이 증가하고, 나머지 증폭기는 출력이 감소하는 동작을 통해 부하 변화에 의한 출력 전력의 변화를 감소시켰다. 부하 변화 구간에서각 증폭기를 balanced로 구성한 구조 대비 효율은 유지하고 출력 전력의 변화는 16.18∼18.46 % 적어지는 시뮬레이션결과를 얻었다. 부하 구간에서 두개의 전력 증폭기를 모두 사용하는 고전력 모드에서 13.54∼21.53 W의 출력 전력 특성과 75.41∼80.16 %의 효율특성을 얻었다. 하나의 전력 증폭기만 동작하는 저전력 모드에서 4.67∼8.76 W의 출력 전력특성과 77.89∼82.48 %의 효율특성을 얻었다.
Design of a Load Modulated Balanced Amplifier with a Two-Stage Control Power Amplifier
Mochumbe Sagini E.,양영구 한국전자파학회 2023 Journal of Electromagnetic Engineering and Science Vol.23 No.3
While an ideal Doherty power amplifier has a linear response, the load modulated balanced amplifier (LMBA) has a compressive response under ideal conditions. This inherent nonlinear characteristic is due to the lower power contribution of the single auxiliary device as the balanced amplifier transistors approach compression. This article presents an LMBA with a two-stage control signal amplifier in place of the single auxiliary device. The idea is to preserve a high and constant gain across the high- and low-power regions by tuning the two-stage gain control signal to match the balanced amplifier gain. An optimal load trajectory can be found for a high-efficiency design by appropriately terminating the second harmonic while ensuring an optimal impedance match in all devices. At the same time, by setting an optimal output power from the auxiliary device, sufficient power is provided to linearize the response of the main power amplifier beyond the output back-off power boundary. As proof of concept, a prototype is designed and implemented. The experimental measurements demonstrate a drain efficiency of 59%–64% at maximum output power and 46%–52% at 7.5 dB output back-off power over the target frequency range of 3.3–3.8 GHz.
김유선,최준표,김민혜,박한기,양세정,김윤섭,김태범,조유숙,오연목,지영구,이상도,김윤근 대한천식알레르기학회 2016 Allergy, Asthma & Immunology Research Vol.8 No.3
Purpose: Recent experimental evidence shows that extracellular vesicles (EVs) in indoor dust induce neurtrophilic pulmonary inflammation, which is a characteristic pathology in patients with severe asthma and chronic obstructive pulmonary disease (COPD). In addition, COPD is known to be an important risk factor for lung cancer, irrespective of cigarette smoking. Here, we evaluated whether sensitization to indoor dust EVs is a risk for the development of asthma, COPD, or lung cancer. Methods: Serum IgG antibodies against dust EVs were measured in 90 healthy control subjects, 294 asthmatics, 242 COPD patients, and 325 lung cancer patients. Serum anti-dust EV IgG titers were considered high if they exceeded a 95 percentile value of the control subjects. Age-, gender-, and cigarette smoke-adjusted multiple logistic regression analyses were performed to determine odds ratios (ORs) for asthma, COPD, and lung cancer patients vs the control subjects. Results: In total, 4.4%, 13.6%, 29.3%, and 54.9% of the control, asthma, COPD, and lung cancer groups, respectively, had high serum anti-dust EV IgG titers. Adjusted multiple logistic regression revealed that sensitization to dust EVs (high serum anti-dust EV IgG titer) was an independent risk factor for asthma (adjusted OR, 3.3; 95% confidence interval [CI], 1.1-10.0), COPD (adjusted OR, 8.0; 95% CI, 2.0-32.5) and lung cancer (adjusted OR, 38.7; 95% CI, 10.4-144.3). Conclusions: IgG sensitization to indoor dust EVs appears to be a major risk for the development of asthma, COPD, and lung cancer.