• 대한전자공학회논문지SD
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• 제39권10호
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• pp.9-15
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• 2002

드리프트 영역에서의 속도 오버슈트 효과를 이용하여 서브밀리미터파 주파수 영역에서 동작하는 새로운 주행 시간 소자를 제안한다. 이 소자를 속도 오버슈트 주행 시간(VOTT) 다이오드라 명명한다. 이 소자는 캐리어 주입 메커니즘으로 빠르게 이루어지는 이종구조 터널링을 이용하며, 속도 오버슈트 효과를 최적화하기 위하여 짧은 드리프트 영역을 갖는다. 변환효율을 증대시키기 위하여 에너지 대역 간극을 경사시키는 방법으로 드리프트영역을 설계한다. 모의실험결과에 따르면 이 소자는 THz 영역에서 동작하리라 기대된다.

• 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.

• E2M - 전기 전자와 첨단 소재
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• 제10권3호
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• pp.268-273
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• 1997

In this paper the transient electron transport in GaAs bulk is simulated by using ensemble Monte Carlo method. To analyze the transient electron transport the 10000 electrons in the .GAMMA. valley are simulated simultaneously for 10 picoseconds. The electric field-velocity relation is obtained. The high impurity density reduces the negative differential resistance effect. The result of transient average velocity shows the electron velocity in the transient state is faster than that in the steady state. This transient velocity overshoot is caused by the intervalley scattering mechanism. And we confirmed the fact that the energy relaxation time is longer than the momentum relaxation time.

• 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.

• 대한기계학회논문집
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• 제10권6호
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• pp.861-869
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• 1986

본 연구에서는 동시확립문제의 속도장해석에 있어서 단면내의 속도분포에 대 한 일체의 가정을 하지 않고 운동량방정식을 직접 해석하여 단면내의 속도분포를 구하 였다. 또한 Prandtl수, 반경비 및 편심도가 열전달특성에 미치는 영향에 대한 해석 도 수행하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제30권1호
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• pp.140-149
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• 2006

Characteristics of a laminar diffusion flame placed near wall in microgravity have been numerically analyzed in a two-dimension. The fuel for the flame is $C_2H_4$. The flame is initiated by imposing a high temperature ignition source. The flow field, temperature field, and flame shape in microgravity diffusion flame are detailed. Especially, effects of surrounding air velocity and fuel injection velocity on the microgravity diffusion flame have been discussed accounting for standoff distance. And, the effect of curvature rate has been also studied. The results showed that velocities in a diffusion flame were overshoot because of volumetric expansion and distribution of temperature showed regularity by free-buoyancy This means that the diffusion flame in microgravity is very stable, while the flame in normal gravity is not regular and unstable due to buoyancy. Standoff distance decreases with increase in surrounding air velocity and with decrease in fuel injection velocity. With increasing curvature rate, the position of reaction rate moves away the wall.

• 한국정밀공학회지
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• 제20권12호
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• pp.89-95
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• 2003

A PID controller integrated with a velocity feedback is designed for fluid power elevator model system in this study. In this case, for outside disturbance load a hydraulic cylinder and a pressure control valve are used. In this method overshoot is reduced and settling time becomes also shorter than the values achieved from the PID controller system only In conclusion a PID controller integrated with a velocity feedback is considered a suitable control method for fluid power elevator system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.349-352
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• 1997

In this paper, we propose a new longitudinal controller of automated vehicles. The controller is designed based on a sliding control method, which is known to be robust to disturbances and modelling errors. Contrary to currently available sliding controller, a switching controller gain method is suggested. It is shown throughout simulations that the proposed controller reduces the amount of overshoot, which may derive smoother velocity tracking in a platoon.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1991년도 춘계학술대회 논문집
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• pp.293-301
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• 1991

A fuzzy regulator for the plant which is composed of CD motor and heavy load is investigated. To have good load regulation and set-point tracking performance, a velocity formed fuzzy control plus linear filter algorithm is proposed. Also a meaning reduction methodfor large inpur whichhas nocontrol rule is presented. Lastly, the performancef of linear PID regulator and fuzzycontroller is compared in terms of response time, overshoot, settling time and control power.

• 전자공학회논문지A
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• 제30A권11호
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• pp.122-131
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• 1993

In this paper, we have developed a submicron Si MOSFET simulator, which is physically based on the hydrodynamic energy transport mode. The simulator was used to investigate the nonstationary transport effects and the transient phenomena in submicron Si MOSFET's. It is found that the velocity overshoot and the carrier heating are dominant transport mechanism near the drain end of the channel and the transient phenomena is more retained in a long channel MOSFET.