• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.135-141
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• 2005

A hybrid central-WENO scheme is proposed. The fifth order WENO-LF scheme is coupled with a central flux scheme at cell face. Two sub-schemes, the WENO-LF scheme and the central flux scheme, are switched by a weighting function. The efficiency and accuracy of the proposed hybrid central-WENO scheme is validated through several numerical experiments.

• Journal of Hydrospace Technology
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• v.2 no.2
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• pp.57-67
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• 1996

The formulation for hybrid-QUICK scheme of convective transport terms in finite-volume calculation procedure is presented. Source terms are modified to apply the hybrid-QUICK scheme. Test calculations are performed for wall-driven cavity flow at Re=$10_2$, $10_3$, and $10_4$. These include the evaluation of boundary conditions approximated by third-order finite difference scheme. The stable and converged solutions are obtained without unsteady terms in the momentum equations. The results using hybrid-QUICK scheme show no difference with those using hybrid scheme at low Re ($=10_2$) and are better at higher Re ($10_3$, and $10_4$).

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1997.03a
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• pp.235-246
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• 1997

Hybrid fuzzy gain scheduling controller is composed of a PD control and a fuzzy control for taking the advantage of each scheme. The key structure of the hybrid fuzzy gain scheduling control scheme is so called a switch which calculates weighting values between the fuzzy controller and the PD controller. However, due to the requirement of the switch , the hybrid fuzzy gain scheduling control scheme needs extra fuzzy logic processing, thus the structure is complicated. and requires more calculation time. To eliminate the drawbacks, a new hybrid fuzzy gain scheduling control scheme is proposed in this paper. In the proposed scheme, the membership function, for calculating of weithting value, and the input and output membership functions are combined. Thus the proposed hybrid scheme does not require switch for calculation of weighting value, and as a result, the calculation time is faster and the structure is more simple than the existing hybrid controller. Computer simulation results for an inverted pendulum model under Pole-Placement PID controller, fuzzy gain scheduling controller,existing hybrid controller , and proposed hybrid controller are compared to demonstrate the good property of the proposed hybrid controller.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1640-1647
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• 1993

The numerical diffusion arising from streamline-to-grid skewness produces a deteriorating effect on the numerical accuracy. The QUICKER scheme to reduce the numerical diffusion requires more computational effort than the HYBRID scheme. This paper deals with the relative computational efficiencies of adopting QUICKER scheme with a coarser grid system and of adopting HYBRID scheme with a denser grid system. Laminar driven cavity flow with Re=400, 1000 is used as a test problem. It is found that QUICKER scheme with a coarser grid system is more efficient than the HYBRID scheme with a denser grid system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.11
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• pp.19-23
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• 2010

In this paper, we propose a combining scheme for partial IR based hybrid ARQ in MIMO systems. The proposed combining scheme is a symbol-level combining scheme for repeatedly transmitted systematic symbols in partial IR based hybrid ARQ. In this paper, it is shown that the proposed combining scheme can also enhance the detection performance of the parity symbols that are newly transmitted in each retransmission. Simulation results show that the proposed combining scheme significantly improves the performance of the partial IR based hybrid ARQ compared to the cases of the conventional bit-level combining scheme, especially with the ZF detection.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.1
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• pp.71-81
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• 1995

In this paper, a new speed control scheme for induction motor drives that regular sampled PWM and harmonic elimination switching pattern over the full range of output speed is presented. The proposed scheme(hybrid scheme) provides three mode and guarantees smooth voltage boost. A detailed description of the scheme, along with the relalization aspect, is described. Moreover, methods of compensating for dead time and optical transmission system of drive signal are proposed and investigated. Finally, experimental investigation of hybrid scheme is presented.

• Journal of Power Electronics
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• v.2 no.2
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• pp.104-111
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• 2002

This paper presents a new hybrid control scheme using Active-Clamped Class-E(ACCE) inverter for the Induction Heating (IH) jar. The proposed hybrid control scheme has characteristics, which acts as class-E inverter at lower switch voltage and ACCE inverter at higher switch voltage than reference voltage of the main switch by feeding back voltage of the switch. The proposedv hybrid control scheme also has advantage of conventional ACCE inverter such as Zero-Voltage-Switch(ZVS) of the main switch and the reduced switch voltage due to clamping cricuit. Moreover, the proposed hybrid control method using ACCE inverter has higher output power than convenional control scheme since ACCE inverter operates like class-E inverter at low input voltage condition. The principles of the proposed control are explained in detail and the validity of the proposed control scheme is verifed through the several interesting simulated and experimental results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.1
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• pp.104-113
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• 1999

A hybrid spatial differencing scheme for the discrete ordinates method is proposed to predict radiative heat transfer in two-dimensional rectangular enclosures. Since this scheme takes the advantages of the diamond scheme and step scheme and includes the characteristics of medium, more accurate and stable results can be obtained. In its development several spatial differencing schemes are examined to address the effect of numerical smearing (or false scattering). Predictions from the proposed hybrid scheme are compared to those of other schemes for transparent, purely absorbing, purely scattering, or absorbing-emitting-isotropically scattering media. It is found that the proposed scheme predicts stable and less smeared results than others.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.3
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• pp.218-226
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• 2003

Due to the friction characteristics of pump, cylinder packing and passenger car, in the elevation system actuated with hydraulic inverter, there exist dead zones. which cannot be controlled by a PID controller. To overcome the drawbacks, in this paper, we propose a new hybrid fuzzy-sliding mode control scheme, which controls the controller output between a sliding mode control output and a PID control output by fuzzy control method. The proposed hybrid control scheme achieves an improved control performance by using both controllers. We first propose a design method of the hybrid controller far a hydraulic system controlled by inverters, then propose a design method of a hybrid fuzzy-sliding mode centre] scheme. The effectiveness of the proposed control scheme is shown by simulation results, in which the proposed hybrid control method yields better control performance then the PID controlled scheme, not only in the zero-crossing speed region but also in the overall control region including steady-state region.

• ETRI Journal
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• v.30 no.5
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• pp.663-673
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• 2008

The multi-scenario topology of multi-channel hybrid ubiquitous sensor networks (USNs) is studied and a novel link auto-diversity cross-layer cooperative scheduling scheme is proposed in this paper. The proposed scheme integrates the attributes of the new performance evaluation link auto-diversity air-time metric and the topology space in the given multi-scenario. The proposed scheme is compared with other schemes, and its superiority is demonstrated through simulations. The simulation results show that relative energy consumption, link reception probability, and end-to-end blocking probability are improved. The addressing ratio of success with unchanged parameters and external information can be increased. The network can tolerate more hops to support reliable transportation when the proposed scheme is implemented. Moreover, the scheme can make the network stable. Therefore, the proposed scheme can enhance the average rate performance of the hybrid USN and stabilize the outage probability.