• 한국전자파학회논문지
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• 제26권2호
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• pp.165-170
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• 2015

본 논문에서는 GaAs 기반 저잡음 증폭기가 사용되고 있는 레이더 수신기의 잡음지수를 낮추고, 저잡음 증폭기의 강인성(robustness)을 위하여 GaN HEMT 기반의 저잡음 증폭기를 설계하고 측정하였다. GaAs 기반의 저잡음 증폭기를 사용하는 레이더 수신기의 경우, 맨 앞단에 저잡음 증폭기를 보호하기 위한 리미터(limiter)가 필요하고, 이는 레이더 수신기 전체 잡음지수를 나빠지게 한다. 본 연구에서 측정한 GaN 기반 저잡음 증폭기의 잡음지수는 2 dB 이하로 측정되었다. 상용화된 GaAs 기반 저잡음 증폭기의 경우, 최대 입력 전력은 약 30 dBm인 반면 본 연구에서는 입력 전력이 43 dBm일 때 소자가 번아웃(burn-out)되었고, 전류 제한 모드로 동작시킬 경우 45.4 dBm에서도 강인성이 보장되었다.

• 생명과학회지
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• 제7권4호
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• pp.342-346
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• 1997

This experiment was carried out to clarify the effects of gibberellin(GA) aplication and bagging on repeening and quality in 'Delaware' grape berries. Treatments are 4 plots(2X2 factorial experiment); GA, GA+bagging, bagging and control. The clusters were dipped twice in 100 ppm GA with GA treatment : 10 days before and after the full bloom. The results obtained as follows: 1. GA treatment made the seedless grape berry reduced in the fresh weight but it hastened the ripening period about 2 weeks. 2. Total soluble solid(TSS), viscosity and pH value of berry juice increased with maturation. The concentration of TSS and viscosity were higher in GA treatment plot than GA non-treatment. 3. Berry-hardness, titratable acidity and alcohol inslouble solid(AIS) decreased with maturation. Expically berry-hardness and AIS decreased more greatly in GA non-treatment than GA treatment. 4. The concentration of anthocyanin increased with ripening but pectic substance didn't fluctuate nearly. These of anthocyanin and pectin were higher in GA non-treatment plot than GA treatment. 5. By analysis of factorial experiment GA treatment was highly significant with the $^{o}$Brix/Acidity ratio, juice viscosity and AIS, but high negatively, significant with berry-hardness and berry fresh weight. And it was significant with T S S and negatively, titratable acidity. Bagging was significant with $^{o}$Brix/Acidity ratio and AIS content, but negatively, titratable acidity. 6. Qualitative characters were high correlated with the $^{o}$Brix/Acidity ratio in simple correlation but direct effect by the path-coefficient analysis didn't coincide with simple correlation. The direct effect of pH was large and juice viscosity, the next. And that of berry-hardness was negligible but, AIS, small negatively.

• 한국인터넷방송통신학회논문지
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• 제22권6호
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• pp.149-154
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• 2022

GaN 소자는 고출력 및 고선형성 특성을 가지므로 레이더 수신기에서 저잡음 증폭기로 활용되어 리미터 없이 구현될 수 있으며, 이로 인해 잡음지수를 개선하고 면적을 줄일 수 있다. 본 논문에서는 Ka-대역 레이더용 수신기에 적용하기 위한 GaN 저잡음 증폭기를 기술하였다. 설계된 저잡음 증폭기는 150-nm GaN HEMT 공정으로 제작되었으며, 목표주파수 내에서 패키징 손실을 포함하여 >23 dB 이득, <6.5 dB의 잡음지수 특성을 보였다. 고입력 부하시험시 이득 및 잡음 저하가 있었으나, 반복시험시 추가적인 성능저하는 나타나지 않았다. 부하시험 후 잡음지수 및 S-파라미터 측정을 통해 GaN 저잡음 증폭기에서 ~40 dBm 펄스 입력 전력을 견딜 수 있음을 확인하였다.

• Current Photovoltaic Research
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• 제2권2호
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• pp.69-72
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• 2014

We investigated current-voltage (I-V) and capacitance (C)-V characteristics of solution-processed thin film solar cells, consisting of $Cu(In,Ga)S_2$ and $CuInS_2$ stacked absorber layers. The ideality factors, extracted from the temperature-dependent I-V curves, showed that the tunneling-mediated interface recombination was dominant in the cells. Rapid increase of both series- and shunt-resistance at low temperatures would limit the performance of the cells, requiring further optimization. The C-V data revealed that the carrier concentration of the $CuInS_2$ layer was about 10 times larger than that of the $Cu(In,Ga)S_2$ layer. All these results could help us to find strategies to improve the efficiency of the solution-processed thin film solar cells.

• 한국전자파학회논문지
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• 제26권6호
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• pp.540-545
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• 2015

본 논문은 GaN(Gallium Nitride) HEMT(High Electron Mobility Transistor) die를 이용하여 S-대역 내부 정합형 전력 증폭기 설계, 제작 그리고 실험 결과에 대해 기술하였다. S-대역 내부 정합형 전력 증폭기를 설계하기 위하여 고유전율을 가지는 기판과 알루미나 기판을 이용하여 입/출력단 정합 회로를 설계 및 제작하였다. 측정 결과로는 펄스 모드로 동작시켰을 때 3 GHz에서 55.4 dBm의 출력 전력, 78 % 드레인 효율 그리고 11 dB의 전력 이득을 얻었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.10-12
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• 1996

AlGaAs/GaAs Heterojunotion Bipolar Transistors (HBTs) with various emitter areas were fabricated and the device size dependence on the current gain was examined. With the different emitter areas, the passivated devices having the same peripheral length were fabricated and measured. The measured base current density in the Gummel plots shows an ideality factor of nearly 2. It is found that as the emitter area becomes small, the base current density with the ideality factor of 2 increases linearly, and as the emitter perimeter/area ratio becomes large, the surface recombination current density component increases. The current gain performance in AlGaAs/GaAs HBTs is mainly determined by either the larger emitter area or the smaller ratio of the emitter perimeter to the emitter area. These results will be compared with experimental works for GaInP/GaAs HBTs

• Bulletin of the Korean Chemical Society
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• 제18권3호
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• pp.311-316
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• 1997

The synthesis and characterization of the mononuclear group 13 heterocyclic carboxaldehyde methyldithiocarbazate complexes Me2M[NC5H4CRNNC(S)SCH3] (M=Al, R=H(1); M=Ga, R=H(2); M=Al, R=CH3(3); M-Ga, R=CH3(4); M=In, R=CH3(5)) are described. Compounds 1-5 were prepared by the reaction of MMe3 (M=Al, Ga, In) with 2-formy or 2-acetylpyridine-S-methyldithiocarbazate in toluene. These compounds 1-5 have been characterized by microanalysis, NMR (1H, 13C) spectroscopy, mass spectra, and single-crystal X-ray diffraction. X-ray single-crystal diffraction analyses reveal that 4-5 are mononuclear metal compounds with coordination number of 5 and N,N,S coordination mode.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 추계학술발표논문집 1부
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• pp.168-171
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• 2010

본 논문에서는 GaN HEMT 소자를 이용한 고출력 고효율 특성을 가지는 광대역 SSPA의 개발을 다루고 있다. 개발한 SSPA는 8W 급과 15W 급의 GaN HEMT 소자를 사용하여 Pre-Drive 증폭단을 구성하였으며, Drive 증폭단은 50W/150W급 GaN HEMT 소자를 직/병렬구조로 사용하였다. Main 증폭단은 4-way 분배기와 결합기를 이용한 Balanced Structure를 적용하여 높은 출력을 구현하였으며, 안정적인 동작을 위하여 음(-)전원 제어 회로와 출력신호 검출 회로를 포함하고 있다. 제작된 SSPA의 사용가능 대역은 2.9GHz~3.3GHz로 단일전원을 사용하고 있으며 100us 펄스 폭, 10% Duty Cycle 조건에서 60dB의 전압이득, 1kW 출력과 약 28% 효율 특성을 가지는 것으로 측정되었다. 본 논문에서 개발한 SSPA는 S-대역을 사용하는 레이더시스템의 송신단에 적용될 수 있다.

• 전자공학회논문지D
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• 제34D권7호
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• pp.15-22
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• 1997

A 10Gbit/s limiting amplifier IC for optical transmission system was implemented with AlGaAs HBT (heterojunction bipolar transistor) technology. HBTs with 2x10.mu. $m^{2}$ and 6x20.mu. $m^{2}$ emitter size were used. The HBT structures are based on metal-organic chemical vapor deposition (MOCVD) epitxy and employ a mesa structure with self-aligned emitter/base and sidewall dielectric passivation. IC was designed to support differnetial input and output. Small signal performance of the packaged IC showed 26dB gain and $f_{3dB}$ of 8GHz. A single ouput has 800m $V_{p-p}$ swing with more than 26dB dynamic range. The performance of the limiting amplifier was verified through single mode fiber320km transmission link test.est.

• 생약학회지
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• 제40권1호
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• pp.32-34
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• 2009

Korean folk medicine 'Ma Ga Mog' has been used as a remedy for rheumatis, cough and bronchitis in Korea. The botanical origin of the crude drug has been no pharmacognostical confirmation on it. To clarify the botanical origin of 'Ma Ga Mog', the anatomical characteristics of the bark of Sorbus amurensis Koehne, S. commixta Hedl. and S. sambucifolia (Cham. et Schltdl.) Roemer var. psuedo-gracilis C. K. Schneid. were studied. As a result, it was clarified that 'Ma Ga Mog' from Korea was the bark of Sorbus amurensis Koehne and S. commixta Hedl.