• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.228-231
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• 2002

This paper describes the design and experimental verification of a hybrid fuzzy control system for a BLDC motor drive. The principle of the proposed control system is to use a PI controller which performs satisfactorily in most cases, while a fuzzy controller, which is ready to take over the PI controller. is used when severe perturbations occur. Thus. the PI and fuzzy controller can be managed to take advantage of their positive attributes.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제16권3호
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• pp.188-196
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• 2016

For the balancing control of a one-wheel mobile robot, CMG (Control Moment Gyro) can be used as a gyroscopic actuator. Balancing control has to be done in the roll angle direction by an induced gyroscopic motion. Since the dedicated CMG cannot produce the rolling motion of the body directly, the yawing motion with the help of the frictional reaction can be used. The dynamic uncertainties including the chattering of the control input, disturbances, and vibration during the flipping control of the high rotating flywheel, however, cause ill effect on the balancing performance and even lead to the instability of the system. Fuzzy compensation is introduced as an auxiliary control method to prevent the robot from the failure due to leaning aside of the flywheel. Simulation studies are conducted to see the feasibility of the proposed control method. In addition, experimental studies are conducted for the verification of the proposed control.

• 음성과학
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• 제15권4호
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• pp.85-96
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• 2008

Automatic speech recognition has severe performance degradation under noisy environments. To cope with the noise problem, many methods have been proposed. Most of them focused on noise-robust features or model adaptation. However, researchers have overlooked utterance verification (UV) under noisy environments. In this paper we discuss UV problems based on the normalized confidence measure. First, we show that UV performance is also degraded in noisy environments with the experiments of an isolated word recognition. Then we observe how the degradation of UV performances is suffered. Based on the UV experiments we propose a modeling method of the statistics of phone confidences using sigmoid functions. For obtaining the parameters of the sigmoidal models, the particle swarm optimization (PSO) is adopted. The proposed method improves 20% rejection performance. Our experimental results show that the PSO-NCM can apply noise speech recognition successfully.

• 한국자동차공학회논문집
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• 제4권3호
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• pp.232-242
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• 1996

In this study, the simulation program for the prediction of volumetric efficiency of the internal combustion engine by the resonator has been developed, when the resonator is mounted on the intake system of 4-cycle SI engines for the improvement of volumetric efficiency. The experimental work has also been carried out for the verification of the program, and it is found that the result of calculation by the simulation program fits qualitatively well with that of experiment. To get the optimal mounting position of resonator on the intake system, the influence of the variation of dimensions of resonator such as neck length, volume and neck diameter were examined by the numerical calculation of the program in advance and the results were compared with the experiments. It is found that the position which is departed 150cm from plenum chamber is better than any other positions, and the average amount of the increase of volumetric efficiency is about 2∼3%

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.379-392
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• 1996

A mathematic model was developed for the simulation of sideways overturning of agricultural tractors on slopes. The overturning motion was described as a combination of the rotational motions with respect to the first and second tipping axes using the principle of conservation of angular mementum. A stability criterion was also established in terms of angular acceleration of tractor about the second tipping axis. Verification of the proposed model was provided by comparing the stability boundaries predicted by computer simulation with those observed experimentally for an equivalent 1/6 scaled mode tractor. A good agreement was shown between the simulation and experimental results.

• 동력기계공학회지
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• 제7권3호
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• pp.69-73
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• 2003

In this paper, the relation between displacement of piezoelectric disk and electric field was proposed. From Navier-Stokes equation and Reynold's equation, the relation between flow and gap of plate was determined. This models were further verified by experiments. Based on theoretical study and experimental verification, the proposed model between flow rate and voltage can be used in the design of mass flow controller in gas supplying system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.72-77
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• 2003

In this paper, an experimental verification of system identification technique for constructing finite element model is conducted for a three-story test structure equipped with an active mass driver (AMD). Twenty Gaussian white noises were used as the input for AMD, and the corresponding accelerations of each floors are measured. Then, the complex frequency response function (FRF) for the input, the force induced by the AMD, was obtained and subsequently, the Markov parameters and system matrices were estimated. The magnitudes as well as phase of experimentally obtained FRFs match well with those of analytically obtained FRFs.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.638-642
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• 2003

This paper presents a parameter design of an Electrorheological(ER) panel for noise reduction using Taguchi method. Taguchi method is a robust design method that determines control parameters in the presence of noise effect. Host structure thickness, spacer thickness, base oil viscosity and the weight ratio of ER particles are chosen for the control factors. A test setup in an SAE J1400 facility is used to analyze the sound transmission loss. The sensitivity of each factor with signal-to-noise(S/N) ratio and analysis of variance are investigated. The analysis results show that the weight ratio of ER particle and base oil viscosity of the ER fluid mostly affects the noise reduction in the presence of electric field. Based on the Taguchi method, an optimal configuration was designed and comparison is made with experimental result fer the verification.

• 한국소음진동공학회논문집
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• 제21권10호
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• pp.924-933
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• 2011

The possibility of noncontact excitation of vibrations in a shaft was investigated in order to enable online structural health monitoring of a shaft during its rotating condition without stop operation. The proposed noncontact exciter was devised to exclusively generate one of two shaft vibration modes, so called longitudinal and flexural. Using the prototypes and a lot of experiments on them, it was proven that bias magnetic field, exciting voltage, center frequency, and geometry of yokes have crucial impacts on its output characteristics.

• 한국정밀공학회지
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• 제20권2호
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• pp.209-217
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• 2003

In this paper, the dynamic system modeling and the state sensitivity analysis of the spin-coater system are proposed for the reduction of the vibration. In the respect of modeling, the spin-coater system is considered to be composed of servomotor, spindle, supporting base and so on. Each component of model is combined and derived to 3 dimensional equations. The combined model is verified by experimental values of actual system in the frequency domain. By direct differentiation of the constraint equations with respect to kinematic design variables, such as eccentricity of spindle, moment of inertia, rotational stiffness and damping of supported base, sensitivity equations are derived to the verified state equations. Sensitivity of design variables could be used for vibration reduction and natural frequency shift in the frequency domain. Finally, dominant design variables are selected from the sensitivity analysis.