• 제목/요약/키워드: carrier velocity

검색결과 173건 처리시간 0.033초

고체입자가 부상된 자유 횡분류 유동에 대한 전산모사 연구 (I) -2상 분류궤적과 운동량 전달기구- (Numerical Simulation Study on Gas-Particle Two-Phase Jets in a Crossflow (I) -Two-Phase Jet Trajectory and Momentum Transfer Mechanism-)

  • 한기수;정명균
    • 대한기계학회논문집
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    • 제15권1호
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    • pp.252-261
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    • 1991
  • 본 연구에서는 2상 횡분류의 평균 유동특성을 비교적 정확히 예측할 수 있는 방법을 제시하는데 있다. 이를 위하여 2상 기체 분류속에 유입되는 자유흐름의 질량 유입을 Keffer와 Baines의 유입함수를 이용하기로 하며, 입자와 기체분류사이의 궤적 이탈을 고려하기로 한다. 이런 모델을 이용하여 2상 횡분류의 분출초기의 입자와 기 체분류의 속도비(particle to gas velocity ratio at the jet exit)가 유동에 미치는 영향을 알아보고자 한다.

Sub-0.1㎛ MOSFET의 게이트전압 종속 캐리어 속도를 위한 정확한 RF 추출 방법 (Accurate RF Extraction Method for Gate Voltage-Dependent Carrier Velocity of Sub-0.1㎛ MOSFETs in the Saturation Region)

  • 이성현
    • 전자공학회논문지
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    • 제50권9호
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    • pp.55-59
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    • 2013
  • Sub-$0.1{\mu}m$로 스케일이 감소함에 따라 기생 저항 효과가 크게 발생되는 dc Ids 측정 데이터 없이 측정 S-파라미터로부터 얻어진 RF Ids를 사용하여 벌크 MOSFET의 포화영역에서 게이트 전압 종속 유효 캐리어 속도를 추출하는 새로운 방법이 개발되었다. 이 방법은 바이어스 종속 기생 게이트-소스 캐패시턴스와 유효 채널 길이의 복잡한 추출 없이 포화영역의 유효 캐리어 속도를 추출할 수 있게 한다. 이러한 RF 기술을 사용하여 벌크 포화 속도를 초과하는 전자 속도 overshoot 현상이 $0.065{\mu}m$ 게이트 길이의 벌크 N-MOSFET에서 관찰되었다.

Extraction of Effective Carrier Velocity and Observation of Velocity Overshoot in Sub-40 nm MOSFETs

  • Kim, Jun-Soo;Lee, Jae-Hong;Yun, Yeo-Nam;Park, Byung-Gook;Lee, Jong-Duk;Shin, Hyung-Cheol
    • JSTS:Journal of Semiconductor Technology and Science
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    • 제8권2호
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    • pp.115-120
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    • 2008
  • Carrier velocity in the MOSFET channel is the main driving force for improved transistor performance with scaling. We report measurements of the drift velocity of electrons and holes in silicon inversion layers. A technique for extracting effective carrier velocity which is a more accurate extraction method based on the actual inversion charge measurement is used. This method gives more accurate result over the whole range of $V_{ds}$, because it does not assume a linear approximation to obtain the inversion charge and it does not limit the range of applicable $V_{ds}$. For a very short channel length device, the electron velocity overshoot is observed at room temperature in 37 nm MOSFETs while no hole velocity overshoot is observed down to 36 nm. The electron velocity of short channel device was found to be strongly dependent on the longitudinal field.

Quasi-Velocity-Matching물 이용한 60 GHz 광캐리어 발생기 (60 GHz Optical Carrier Generator using Quasi-Velocity-Matching Technique)

  • 김우경;양우석;이형만;이한영;정우진;권순우
    • 한국광학회지
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    • 제17권2호
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    • pp.181-185
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    • 2006
  • 리튬나이오베이트 기판의 분극 반전 기술을 이용하여 300Hz 대역 광변조기를 제작하였고 60 GHz 광캐리어 발생기로 응용하였다. 주기적인 분극반전은 도파광과 RF사이의 QVM(Quasi-Velocity-Matching)을 유발하여 대역변조를 가능하게 하였다. 제작된 광변조기는 30.3 GHz에서 최대 변조효율을 보였으며, 3 dB 변조 대역폭은 약 5.1 GHz로 측정되었다. DSB-SC(Double Sideband Suppressed Carrier) 측정 실험을 통해 입사된 광 주파수로부터 30 GHz 간격으로 USB(Upper Sideband)와 LSB(Lower Sideband)를 발생시켰으며 입사광의 스펙트럼은 발생된 USB 혹은 LSB에 비해 28 dB정도 억제됨으로써, 30GHz 대역 광변조기가 60 GHz 광캐리어 발생기로 응용될 수 있음을 보였다.

환경 에너지 시설 내 발효조, 소화기 및 건조기 유동해석 (Flow analysis of fermenter, digester and dryer environmental in energy facilities)

  • 전용한
    • Design & Manufacturing
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    • 제13권4호
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    • pp.28-33
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    • 2019
  • In this study, the flow analysis of fermentation tank, digester and dryer, which are the main equipment in environmental energy facilities, was carried out. Numerical analysis was carried out with the size of the actual plant, and 3D modeling program CATIA V5 R16, grid generation program Gambit, and general purpose flow analysis package ANSYS-FLUENT (v13) were used. Simulation results of the carrier gas flow analysis in the STD dryer using the computational fluid dynamics program showed that the carrier gas smoothly circulated between the shells of the dryer and the flow was uniformly distributed without stagnation or flow. It is also predicted that rotational flow due to shell rotation is active. The average flow velocity of carrier gas in the STD dryer was estimated to be about 0.196m / s, and the average temperature of the carrier gas was calculated to be 424K. Due to the relatively slow carrier gas velocity and high average temperature, the water content of the sludge can be effectively lowered.

케미컬루핑 연소를 위한 산소전달입자의 최소유동화속도 및 고속유동층 전이유속에 미치는 압력의 영향 (Effect of Pressure on Minimum Fluidization Velocity and Transition Velocity to Fast Fluidization of Oxygen Carrier for Chemical Looping Combustor)

  • 김정환;배달희;백점인;박영성;류호정
    • 한국수소및신에너지학회논문집
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    • 제28권1호
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    • pp.85-91
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    • 2017
  • To develop a pressurized chemical looping combustor, effect of pressure on minimum fluidization velocity and transition velocity to fast fluidization was investigated in a two-interconnected pressurized fluidized bed system using oxygen carrier particle. The minimum fluidization velocity was measured by bed pressure drop measurement with variation of gas velocity. The measured minimum fluidization velocity decreased as the pressure increased. The transition velocity to fast fluidization was measured by emptying time method and decreased as the pressure increased. Gas velocity in the fuel reactor should be greater than the minimum fluidization velocity and gas velocity in the air reactor should be greater than the transition velocity to fast fluidization to ensure proper operation of two interconnected fluidized bed system.

Dynamic Response and Carrier Velocity in Organic Field-Effect Transistors

  • Cobb, Brian;Wang, Liang;Dunn, Lawrence;Dodabalapur, Ananth
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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    • pp.60-63
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    • 2009
  • In this letter we report on the carrier velocity of polycrystalline pentacene transistors as a function of electric field. We performed a series of measurements on devices with a range of channel lengths. At moderate electric fields (<$5{\times}10^5$ V/cm), the characteristics are similar to those of disordered or amorphous organic semiconductors. The highest velocities we have measured are near $6{\times}10^4$ cm/s at room temperature. We perform quasi-static and dynamic measurements to measure carrier velocity. These results fill an important void between experimental results that have been obtained with disordered/amorphous organic semiconductors and single crystals.

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0.5 MWth 케미컬루핑 연소시스템 적용을 위한 산소전달입자의 수력학 특성 및 고체순환 특성 (Hydrodynamics and Solid Circulation Characteristics of Oxygen Carrier for 0.5 MWth Chemical Looping Combustion System)

  • 류호정;김정환;황병욱;남형석;이도연;조성호;백점인
    • 한국수소및신에너지학회논문집
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    • 제29권6호
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    • pp.635-641
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    • 2018
  • To select the operating condition of 0.5 MWth chemical looping combustion system, minimum fluidization velocity, transition velocity to fast fluidization and solid circulation rate were measured using mass produced new oxygen carrier (N016-R4) which produced by spray drying method for 0.5 MWth chemical looping combustion system. A minimum fluidization velocity decreased as the pressure increased. The measured transition velocity to fast fluidization was 2.0 m/s at ambient temperature and pressure. The measured solid circulation rate increased as the solid control valve opening increased. We could control the solid circulation rate from 26 to $93kg/m^2s$. Based on the measured minimum fluidization velocity and transition velocity to fast fluidization, we choose appropriate operating conditions and demonstrated continuous solid circulation at high pressure condition (5 bar-abs) up to 24 hours.

GPS의 반송파 위상을 이용한 각속도 계산 알고리즘 (The computation algorithm for angular rate using GPS carrier phase)

  • 박준구;김진원;이장규
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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    • pp.1338-1341
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    • 1997
  • In this paper, we propose angular rate computation algorithm using GPS carrier phase. A direct angylar rate masurement has not previously been available form GRS, although its availability is highly desirable for use in state feedback control. So we propose angular rate computationalgorithm which derive angular rate from the velocity of differentiated carrier phase og GPS. The proposed algorithm contains attitude determination using double-differentiated carrier phase and 2 baseline configuration whcih provide more practical applications than 3 baseline.

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INS 속도 정보를 사용한 GPS 반송파 추적 루프의 성능 향상 (Performance Improvement of INS Velocity-aided GPS Carrier Tracking Loop)

  • 김정원;이상정;황동환
    • 제어로봇시스템학회논문지
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    • 제12권8호
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    • pp.739-745
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    • 2006
  • This paper presents performance improvement of the INS velocity-adided GPS carier tracking loop. To this end, INS velocity-aided GPS carrier tracking loop was modeled as a feedfoward and a feedback loop system. In the phase tracking loop, it was shown that the tracking error caused by the dynamic motion of the vehicle can be compensated with the aiding of the INS information irrespective of the loop order and bandwidth. However, the signal trcking error increases as the INS error increases. It was also shown that in order to remove the tracking error caused by INS bias error, more than or equal to 2nd order PLL should be used. Experiments were carried out and the experimental results were compared with the analysis results.