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A Simplified Broadband Output Matching Technique for CMOS stacked Power Amplifiers
KO, Jaeyong,KIM, Kihyun,SONG, Jaehoon,NAM, Sangwook 'Institute of Electronics, Information and Communi 2014 IEICE transactions on electronics Vol.97 No.10
<P>This paper describes the design method of a broadband CMOS stacked power amplifier using harmonic control over wide bandwidths in a 0.11 mu m standard CMOS process. The high-efficiency can be obtained over wide bandwidths by designing a load impedance circuit as purely reactive as possible to the harmonics with broadband fundamental matching, which is based on continuous Class-F mode of operation. Furthermore, the stacked topology overcomes the low breakdown voltage limit of CMOS transistor and increases output impedance. With a 5-V supply and a fixed matching circuitry, the suggested power amplifier (PA) achieves a saturated output power of over 26.7 dBm and a drain efficiency of over 38% from 1.6 GHz to 2.2 GHz. In W-CDMA modulation signal measurements, the PA generates linear power and power added efficiency of over 23.5 dBm and 33% (@ACLR = 33 dBc).</P>
디지털 방송 시스템에서의 방송 데이터 처리를 위한 메시지 캐슁 기반의 데이터 캐루셀 매니저
원재훈(Jaehoon Won),김세창(Sehchang Kim),고상원(Sangwon Ko),전제민(Jaemin Jeon),김정선(Jungsun Kim) 한국정보과학회 2007 한국정보과학회 학술발표논문집 Vol.34 No.2D
국내외 방송환경이 디지털로 급속히 변화함에 따라서 지상파, 케이블, 위성 등의 기존 방송망을 이용하여 서비스 제공자가 제공하는 데이터 서비스를 사용자가 요청 할 때 전송하는 데이터 방송은 기존의 비디오, 오디오 방송 프로그램 이외에 방송과 관련된 데이터 또는 방송과는 직접 관련이 없는 순수한 데이터를 제공하게 되었다. 데이터 방송 표준 단체인 DVB(Digital Video Broadcasting)에서는 데이터 방송 시 데이터 전송 기법으로 데이터 스트리밍(Data Streaming), 데이터 파이핑(Data Piping), 데이터 캐루셀(Data Carousel), 멀티프로토콜 인캡슐레이션(Multiprotocol Encapsulation), 객체 캐루셀(Object Carousel)을 제안하고 있다. 본 논문에서는 데이터 방송에 사용되는 데이터를 효율적으로 처리하기 위하여 메시지 캐슁과 모듈 캐슁을 기반으로 한 데이터 캐루셀 매니저 설계와 구현에 관한 내용을 다룬다.
Lim, Jaehoon,Bae, Wan Ki,Park, Ko Un,zur Borg, Lisa,Zentel, Rudolf,Lee, Seonghoon,Char, Kookheon American Chemical Society 2013 Chemistry of materials Vol.25 No.8
<P>We report scalable controlled synthesis of CdSe tetrapods with high morphological uniformity based on the continuous precursor injection (CPI) approach with halide ligands. The CPI approach involves the successive injection of precursors into the seed solution at a controlled rate so that the reaction condition remains in the kinetic growth regime. To initiate the successful development of tetrapod structure, the controlled amount of halide ligands are added during the reaction, which triggered the formation of wurtzite arms on {111}-facets of the zincblende seeds. The formation of the wurtzite phase is responsible for the halide-mediated displacement of oleate ligands, destabilizing the embryonic CdSe phase on the zincblende seeds enabling the phase transformation to more stable wurtzite phase on the hexagonal {111}-facets. On the basis of these halide-mediated phase transformation of CdSe nanocrystals and the persistent kinetic growth induced by the CPI approach, well-defined CdSe tetrapods with controlled arm length and diameter have been produced in large quantity.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2013/cmatex.2013.25.issue-8/cm3035592/production/images/medium/cm-2012-035592_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm3035592'>ACS Electronic Supporting Info</A></P>
Environmentally benign nanocrystals: challenges and future directions
함동효,Donghyun Ko,정병국,Sohee Jeong,Jaehoon Lim,Wan Ki Bae,Changhee Lee,Kookheon Char 한국정보디스플레이학회 2019 Journal of information display Vol.20 No.2
Colloidal semiconductor nanocrystals, referred to as quantum dots (QDs), have unique and superb photophysical properties, promising a variety of applications ranging from optoelectronics and energy harvesting to agriculture. The last decade witnessed a tremendous advance in QDs and their successful debut in displays, and now, QDs are equipped with environmental benignity to expand their territory to everyday life. From this perspective, the current research status and future perspective of environmentally benign QDs as building blocks for light-generating and light-harvesting applications are provided. Also provided is an overview of the progress made in the chemistry (colloidal synthesis, surface chemistry, and heterostructuring) and in their photophysical and electrical properties from the viewpoint of their use in light-emitting or light-harvesting applications. Grounded on the current status of heavy-metal-free QDs compared with cutting-edge technologies, the perspective of environmentally benign QDs for practical use and future research directions is discussed.
Kyusun Cho,Jaehoon Ko,Seungryong Kim 대한전자공학회 2023 대한전자공학회 학술대회 Vol.2023 No.6
This paper explores the application of 3D-aware GANs in video editing, specifically addressing challenges related to identity preservation and temporal consistency. We propose an optimizationbased inversion pipeline that maps consecutive frames of a portrait video to the latent space of 3Daware GANs. Novel 3D-aware loss functions are employed to reinforce the optimization of latent codes and camera viewpoint, ensuring temporal coherency using estimated optical flow. Additionally, we introduce a strategy to enhance visual quality by addressing focal length inconsistency in each frame. Extensive experiments demonstrate that our method outperforms previous video GAN inversion techniques, maintaining identity and temporal consistency while achieving comparable visual quality and manipulation capabilities. Furthermore, we showcase the versatility of our approach by applying it to tasks such as head pose control and 3D shape generation. This research sheds light on the potential of 3D-aware GANs in video editing, opening new possibilities for future exploration and practical applications.
Power and Trim Estimation for Helicopter Sizing and Performance Analysis
Vaitla Laxman,JaeHoon Lim,SangJoon Shin,KwangHo Ko,SungNam Jung 한국항공우주학회 2011 International Journal of Aeronautical and Space Sc Vol.12 No.2
The preliminary design stage of helicopters consists of various operations and in each operation design several detailed analysis tasks are needed. The analysis tasks include performance and the required power estimation. In helicopter design, those are usually carried out by adopting the momentum theory. In this paper, an explicit form of computational analysis based on the blade element theory and uniform/non-uniform inflow model is developed. The other motivation of the present development is to obtain trim and required power estimation for various helicopter configurations. Sectional and hub loads, power, trim, and flapping equations are derived by using a symbolic tool. Iterative computations are carried out till convergence is achieved in the blade response, inflow, and trim. The predictions regarding the trim and power estimation turn out to be correlated well with the experimental results. The effect of inflow is further investigated. It is found that the present prediction for the lateral cyclic pitch angle is improved with the non-uniform inflow model as compared to that by the uniform inflow model. The presently improved trim and power estimation will be useful for future helicopter sizing and performance analysis.
스크램제트 추진 시스템의 비행 제어를 통한 연소기의 추력 분석
고효상(Hyosang Ko),양재훈(Jaehoon Yang),여재익(Jai ick Yoh),최한림(Hanlim Choi) 한국추진공학회 2021 한국추진공학회지 Vol.25 No.1
The PID controller with fin angle and thrust as control input was designed based on the aerodynamic data of scramjet system. Flight simulation following a given trajectory which strike the target point after climb and cruise with constant dynamic pressure was conducted. After that, the required thrust for the climb and cruise was calculated and the required fuel flow rate for the hydrogen fuel dual mode scramjet combustor was analyzed. The combustor analysis of this study which conducted on integrated model of independently developed inlet, combustor, nozzles and external aerodynamic models, laying the foundation for the integrated design of the air breathing hypersonic system.
토크 제어 로봇을 위한 복합 테스트플랫폼의 설계 및 성능 검증
고종성(Jongseong Ko),심재훈(Jaehoon Sim),정재석(Jaesug Jung),황순욱(Soonwook Hwang),박재흥(Jaeheung Park) 제어로봇시스템학회 2019 제어·로봇·시스템학회 논문지 Vol.25 No.12
In this paper, we propose a test platform that can have various configurations according to the research needs and can be easily modified by additional installation of specific functional modules. Various experiments can be conducted by changing the dynamic characteristics of actuators, the rigidity of the joint through additional SEA module, and the robot assembly configuration from horizontal to vertical articulated type. In addition, controllers and encoders were selected to perform torque control experiments well. It is also designed to facilitate further modifications. Therefore, using the proposed test platform in this paper, we expect to be able to measure more reliable, stable and consistent data in an environment where we can freely create new combinations while sharing major modules. It is also expected to contribute significantly to the reduction of research period and cost.