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A closedloop control system to reduce the harmonics required by PWM controlled single phase Active AC power filter is proposed. The instantaneous harmonics which consist of both displacement of fundamental current and harmonic distortion current is measured and compensated by Active power filter connected parallel between power lines and nonlinear load. A combination of a D.C choke and a transistor Inverter is used for the Active power filter. The principal and the construction of the control system are presented as well as some experimental results. The results are obtained as follows. 1) The reactive power including both displacement of fundamental current and harmonics distortion current of 1.5[KHz] and below can be eliminated. By the use of closed―loop control, the accuracy of compensation is excellent. 2) The voltage fluctuation of power supply is not disturbed, because the power is improved from 0.65 to 0.96 by the use of Active power filter. 3) Fast response of 8.3[㎳] for quick changes of the load can be attained. 4) Because of using a power transistor as the switching element of the current type PWM Inverter, the compensating time is more improved and commutation loss in Inverter becomes nearly zero. 5) In order to eliminate harmonic current of more than 1.5[KHz], the PWM Inverter using as Active power filter must be multi―current type.
Data acquisition of fast timevarying phenomena is relevant to voltage measurement such as speed retrieval of data for analysis, number of channels, etc. To overcome these limitation, a softwarebased high speed Multichannel Data Acquisition system has been designed and developed. The prototype hardware assembly consists of R6502 microprocessor, 8 bit A/D converter with 8 channel analog multiplexer and related interface circuitry. The data are stored in 32k byte DRAM memory and the stored data are retrieved by a low speed system clock through a digitaltoanalog converter onto an XY recorder.
A control system of brushless dc machine position control based on Variable Structure System approach is presented. In order to simplify the overall control system and to improve the robustness of position controller, a new switching function which composed of linear combination of only measurable state variables Sr(x) and Sr(x) is defined. With this proposed method, good dynamic and steady state behaviors of the overall system are obtained without any external load torque observer. A general PWM amplifier is replaced by an ON―OFF pattern generator for digitalization and a digital signal processor(DSP) is used for high speed switching. Experimental results are given to demonstrate the validity of the proposed control method.
Traditionally, the model for power switching circuits at harmonic frequencies connected to an ac system has been an ideal current source. The magnitudes of the currents at each frequency are derived from the anaiysis of idealized current waveform. These currents are injected into the ac system to determine the resonant frequencies and harmonic penetration into the system. A more accurate model for frequency plane analysis is proposed and it is applied to a static VAR compensator(SVC) consisting of a fixed capacitor in parllel with a thyristor controlled reactor(FCTCR). This model consists of a harmonic voltage source in series with a variable source admittance. The differential equations for the system are first written in order to gain a better insight to the problem. The model is hypothesized and the circuit is analyzed to determine its parameters. Finally, the results of a model test is shown which verify the accuracy of the model.
The purpose of this study was to analyze the causal relationship between sports desire, sports commitment and sports goal trend of social baseball club member and find out which parameters gave impacts to them empirically. The questionnaires were performed to 200 people. The result of path analysis about each factor revealed that there was a significant difference between sports desire and sport goal trend (β=.281) and the explained variance of final regression model was 9.7%(F=12.161, p<.001). In addition, there was a negative significant difference between sports commitment and sports goal trend(β=-.163) and the explained variance of final regression model was 0.5%(F=.013, p<.001). There was no significant difference between sports desire and sports commitment(β=.008) and the explained variance of final regression model was 0.5% (F=.013, p<.001). Here, the important fact was that sports commitment was an important parameter to reinforce the relationship between sports desire and sports goal trend.