• 전자공학회논문지B
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• 제30B권1호
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• pp.38-44
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• 1993

A model for BICMOS buffer switching operation is presented, including the influence of bipolar base transit time and collector-base capacitances. A closed-form solution for the propagation delay-time is obtained assuming low level injection and channel velocity limitation. For the high level injection case, the delay-times are numerically obtained using effective current gain. These results are compared with those by HSPICE simulation, which shows good agreement. It is noted that the collector-base capacitance strongly affects the delay-time. The effects of voltage scaling are also investigated, which shows the model can be applied for the reduced supply voltages.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.500-505
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• 2009

This paper presents temperature control of engine cooling system using a controllable magnetorheological (MR) fan clutch. An appropriate size of MR fan clutch is devised and modeled on the basis of Bingham model. Subsequently, an optimization to determine design parameters such as width of housing is undertaken by choosing the reciprocal of the controllable torque as an objective function. Under consideration of spatial limitation, design parameters are optimally determined using finite element analysis. A sliding mode controller is then designed to control the angular velocity of the MR fan clutch using experimentally determined parameters. The designed controller is experimentally implemented and control performances of the MR fan clutch system are evaluated.

• 한국전문물리치료학회지
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• 제7권2호
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• pp.55-65
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• 2000

The purpose of this study was to compare the effects of anterior walker and posterior walker on gait parameters and body alignment of children with cerebral palsy. The intraclass correlation coefficient was .99 for intertester reliability. Intratester reliability was between .96 and .99. The use of posterior walker increased gait velocity and facilitated more upright posture. The measurement of joint angle program was found to be reliable to measure range of motion. This study has a limitation of generalizing the results to all children with cerebral palsy. Research is required to investigate the effect of posterior walker on energy efficiency.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1797-1801
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• 2004

In this paper we show the hardware testbed and software simulator of multi function array radar (MFAR). The hardware MFAR is simple and flexible hardware to implement various radar beamforming and detecting algorithms. To overcome the limitation of hardware MFAR, the software simulator is proposed. User can simulate radar under the various environment conditions adjusting the parameter of simulator. User can set environment of radar, such as the location and velocity of target, jammer and the terrain clutter. The radar use various probing pulses and supports two operation mode, surveillance and tracking mode.

• 대한기계학회논문집A
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• 제30권11호
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• pp.1401-1407
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• 2006

In a haptic interface system with a nanoscale virtual environment (NVE) using an atomic force microscope (AFM), impedance scaling is important. In order to explicitly derive the relationship between performance and impedance scaling factors, a nanoscale virtual coupling (NSVC) concept and a selection method of scaling factors of velocity (or position) and force are introduced. An available scaling factor region is represented based on Llewellyn's absolute stability criteria and the physical limitation of the haptic device. Experiments have been performed for tele-nanomanipulation tasks such as positioning, indenting and nanolithography with available force scaling factor in the NVE.

• 한국소음진동공학회논문집
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• 제20권1호
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• pp.51-57
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• 2010

This paper presents temperature control of engine cooling system using a controllable magnetorheological(MR) fan clutch. An appropriate size of MR fan clutch is devised and modeled on the basis of Bingham model. Subsequently, an optimization to determine design parameters such as width of housing is undertaken by choosing the reciprocal of the controllable torque as an objective function. Under consideration of spatial limitation, design parameters are optimally determined using finite element analysis. A sliding mode controller is then designed to control the angular velocity of the MR fan clutch using experimentally determined parameters. The designed controller is experimentally implemented and control performances of the MR fan clutch system are evaluated.

• 물과 미래
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• 제8권2호
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• pp.75-80
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• 1975

The fluvial phenomena in the bended natural river course are studied experimentally. Some theoretical and empirical conclusions were derived in prior to this study by some authors but the limitation of applicability of those results are not clearly known because of the sensitibitys of the flow regime in the reach. The main objective of this study is directed to evaluate the mechanism of sedimentation and the cross sectional changes in the equilibrium status. the most governing factor influenced to the cross sectional changes in the bended reach is the occurance of spiral flow. In this study, the streamlines and velocity distributions are checked at given interval by the hydraulic model to find out the place where spiral flow are existing under the various flow magnitudes.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 춘계학술대회 논문집
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• pp.108-119
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• 2001

The Spectral Analysis of surface Waves(SASW) Method has a great has a great potential for rapid determination of shear wave velocity profile of ground. However, it has an inherent limitation in the interpretation of test results due to the assumption that the ground is layered horizontally. The reason of the assumption is that difficulties exist in obtaining analytical solutions of wave equation when a soil system is composed of inclined soil layer. In this study, a finite-element method has been employed to assess the effects of dip angle and stiffness contrast of inclined soil layers and the testing direction on the dispersion curve. The propagation of wave front in the inclined soil layer was also investigated. The results indicated that the influence of dip angle on the dispersion curve is getting obvious as the dip angle increases and the propagation of wave front in the inclined layer also entirely different compared with the case of the horizontal layer.

• 대한전자공학회논문지
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• 제27권10호
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• pp.89-95
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• 1990

동작 속도와 용량성 부하에 따른 최적소자크기를 결정할 수 있는 bipolar-CMOS 버퍼 모델을 제안한다. 면적 최적화를 위한 해석적 결과를 바이폴라의 고주입 효과 및 MOS의 챠넬 속도제한영역을 가정하여 구했다. BICMOS 버퍼의 면적은 용량성 부하에 거의 비례하는 에미터 길이와 챠넬 폭을 정함으로써 최적화된다는 것을 보이고, 회로 세뮬레이션 결과와 비교하여 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.828-833
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• 2003

Rigid plate elastically supported at the edges is modeled and the performance of the optimal vibration control under sinusoidal excitation is tested. The controller based on the linear quadratic regulator with output feedback is designed to control the multi-degree of freedom vibration. Relative weighting parameters are considered as design constraints to determine the limitation of maximum control force and state parameters. Control force calculated by proportional output feedback of the displacement and velocity is used to suppress the vibration induced by the sinusoidal external force. The active vibration control of vibrating plate by the LQR controller is examined through the numerical simulations that show the effectiveness of optimal control scheme on the three degrees of freedom structure.